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      01-27-2023, 07:27 PM   #1
Serf27
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O2 sensors showing 0 voltage.

2009 328i N52.
136k miles
SES light turned on.
2C7E-Oxygen sensor control
2C6B-Oxygen sensor after catalytic converter-System check
Both codes suggest switched O2 sensor connectors. They arenít switched.
Diagnostic says replace bank 1, post cat sensor first then pre cat sensor.

I check live data voltage:
Voltage Lambda Probe Behind Cat 1: 0V at idle/revving
Voltage Lambda Probe Hinterkat1: 0V at idle/revving.
I have not actually checked the connectors with a voltmeter.

I read a few threads where people have reset the engine adaptions and started seeing voltage.
Iíve also read about adaptions reset causing issues.
Before I replace bank1 O2 sensors? Should I try resetting engine adaptions?

I compared STFT/LTFT side by side with another 09 and they were very close to being the same readings.

Thanks.
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Last edited by Serf27; 01-30-2023 at 09:19 PM..
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      01-27-2023, 09:53 PM   #2
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What Scan Tool or Diagnostic Software (INPA/ISTA) do you have to read PRE-CAT (Vor Kat) Lambda Sensor Voltage? On my 3/2007 build 328xi N52KP, the Pre-Cat O2 Sensor Voltage has always been between 1.98V & 2.06V, using 2 different versions of INPA, and ISTA, and Post (hinter) cat sensor voltage is .70 to .72 volts.

Some Scan Tools, and even some versions of INPA, are NOT programmed correctly to "query" (HACK ;-) some parameters that other tools or software versions DO display correctly. I don't know if it's a typo or what, but one 0V reading you say is "Behind Cat 1" and the other is "HinterKat 1". My understanding is HinterKat 1 means O2 Sensor Behind/Downstream of Cat on Bank 1 (forward Manifold).

If you have either INPA or ISTA, try that, or let me know and I'll provide Menu Path. Also, let me know if you need a wiring diagram, component location, or Connector View for the Sensors & their connectors. My SWAG is that you either have a wiring/connector issue, or issue with Scan Tool, if you are seeing "0" Volts on ANY of the 4 sensors.
George
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      01-27-2023, 10:44 PM   #3
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Iím using bimmergeeks protools app.

Looking at the photos of the readings I took, I now see that pre cat bank 1 sensor does read 2V.
Bank2 pre cat reads 1.8V
Bank2 post cat reads .7V

I did not know what ďHinterkatĒ meant, I assumed it was post catÖ

So it looks like the I am only receiving no voltage to bank 1 post cat sensor.

I had a previous code for bank 2 post cat O2 sensor. I disconnected both post cat connectors and sprayed electrical cleaner on them. This did not solve the Bank2 post cat(sensor 2) issue, but it did create the new issue, I am guessing.
I replaced the Bank2 post cat sensor today.
That code is now gone, but Iím left with this.

Is it possible the cleaner did some damage to the sensor?

Menu path? Is that where it takes you through the diagnostic steps?
Yes, if you could share those please.
Can you also share what pins I should be measuring at the bank1 post cat sensor to look for voltage or other readings on that connector? Itís the 4 pin round connector.

Protools did list diagnostic steps for each error and theyíre both the same:

FAULT STRATEGY
This fault automatically triggers an active test (secondary fault stored in the control modules fault memory).
- 1 Read out, results of active test (are other fault codes still stored in the fault memory?
=õ Then continue at/this pointi)
2. Initiate system fest for reversed O2 sensors, Follow instructions for system test

I donít know what that test is for Step 2. No connectors are
swapped/reversed.


3. If the system test fails to produce a result then.
4. Visual inspection of wiring and plugs.
Wiring and plugs are ok.

5. Electrical check of wiring
Hereís where Iím stuck, wiring of Bank 1 O2 sensors?

6. Replace wiring or plugs as indicated
7. Check exhaust system forward of downstream (post -cat) 02 sensor for leaks
No leaks

8 Replace downstream (post-cat) 02 sensor
9. Replace upstream (pre-cat) 02 sensor
10. Replace control module

Hereís the live data of O2 voltage readings I have-Engine was at operating temp.
Thanks.
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      01-28-2023, 12:13 PM   #4
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Quote:
Originally Posted by Serf27 View Post
I’m using bimmergeeks protools app. [ProTool appears to show the data in BOTH English AND German. Vorkat means before, or in front of Catalytic Converter, and Hinterkat means behind Cat.
https://translate.google.com/?sl=de&...&op=translate]

So it looks like the I am only receiving no voltage to [my interpretation is that is Voltage Received by DME from] bank 1 post cat sensor...Is it possible the cleaner did some damage to the sensor? [If the Electronic Contact Cleaner was ONLY sprayed on the Electrical Connectors, and NOT on the Sensor itself, I don't see how that could affect sensor function adversely. Such things as Silicone (even engine oil) may contaminate sensor, causing failure.]
Menu path? Is that where it takes you through the diagnostic steps? ["Menu Path" or Menu Sequence is a term I use to mean the buttons you push or click on to view a certain screen -- a sequence of Menu Selections. "Calculate Test Plan" is the ISTA button you select, at the Fault Memory List, after selecting a particular fault code, if more than one, to get "Directed Diagnosis". I'm NOT aware that ProTool has such capability.]
Yes, if you could share those please. [If you have ISTA, See attached pdf, "ISTA Fault Memory & Test Plan". If you have INPA and want to know what screens to view & HOW, please indicate.]
Can you also share what pins I should be measuring at the bank1 post cat sensor to look for voltage or other readings on that connector? It’s the 4 pin round connector. [I'll attach ISTA Lambda Control ScreenPrints for Post-Cat Sensors/ Connectors & interpret below.]...
I don’t know what that test is for Step 2. No connectors are
swapped/ reversed.
[I presume there is such a test in ISTA, but I have NOT used it. There IS a test for "Swapped" (Vertauschte) Connectors: INPA > F9 System Diagnoses > F4. If you're BENEATH the car, easy enough to check wire colors at Pin #3, whether Black/Red (Bank 1), or Black/Green (the vehicle harness side of connector).]...
Here’s where I’m stuck, wiring of Bank 1 O2 sensors? [See Below]...
It would appear from the Live Data that what we need to determine is WHY the Post/Hinter Cat Sensor on bank 1 has "0" voltage as received by DME.
I would emphasize that I have NOT had an O2 sensor issue on mine and have NOT personally tested the system. I do NOT know how the DME goes to "Closed Loop"/ Active, and have NOT even determined how LONG after cold start that occurs. So simply testing with Ignition on, Engine OFF, may NOT disclose anything.

ANYONE with electronics training who can interpret the symbols in the SSP, please enlighten us.

Here is my interpretation of the attached SSP wiring diagram and HOW to test with Multimeter:
1) With Sensor detached from connector, and measuring voltage in reference to Chassis Ground, there should be 12V+ battery voltage at the HEATER wire, X62102/1 (Orange wire), with Ignition ON & KL87 Active. I see NO indication that power supply is pertinent to Sensor function however, as that should ONLY be heating element power supply.

2) Also with Sensor detached: When system goes "Closed Loop"/ Active, there should be voltage at the Yellow wire, X62102/4. Exactly WHAT that voltage is (5V, 12V?) and WHEN/ HOW to get voltage there?
I would suggest test Bank 2 connector to get determination of what "Properly-functioning" bank shows (AND please let us know what you find ;-).

3) I would also measure Voltage (in reference to chassis ground) at X62102, using a pin or "Backprobe" with Sensor CONNECTED to Chassis Connector. If you are getting voltage in (2) but not in this test, then the Sensor or its wiring (between sensor & connector) has an issue.

That's all I know and the "best I can do": The REST is up to you and we await ENLIGHTENMENT.
George
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      01-28-2023, 12:18 PM   #5
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Those ScreenPrints were reduced too much, so here are last two at 100%. Hopefully you can actually READ these.
George
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      01-28-2023, 01:08 PM   #6
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Quote:
Originally Posted by gbalthrop View Post
It would appear from the Live Data that what we need to determine is WHY the Post/Hinter Cat Sensor on bank 1 has "0" voltage as received by DME.
I would emphasize that I have NOT had an O2 sensor issue on mine and have NOT personally tested the system. I do NOT know how the DME goes to "Closed Loop"/ Active, and have NOT even determined how LONG after cold start that occurs. So simply testing with Ignition on, Engine OFF, may NOT disclose anything.

ANYONE with electronics training who can interpret the symbols in the SSP, please enlighten us.

Here is my interpretation of the attached SSP wiring diagram and HOW to test with Multimeter:
1) With Sensor detached from connector, and measuring voltage in reference to Chassis Ground, there should be 12V+ battery voltage at the HEATER wire, X62102/1
X62101 is referring to Bank1 and X62102 is bank2?

(Orange wire), with Ignition ON & KL87 Active. I see NO indication that power supply is pertinent to Sensor function however, as that should ONLY be heating element power supply.

2) Also with Sensor detached: When system goes "Closed Loop"/ Active, there should be voltage at the Yellow wire, X62102/4.
I do not see X62104 in the diagrams you posted.

Exactly WHAT that voltage is (5V, 12V?) and WHEN/ HOW to get voltage there?
I would suggest test Bank 2 connector to get determination of what "Properly-functioning" bank shows (AND please let us know what you find ;-).

3) I would also measure Voltage (in reference to chassis ground) at X62102, using a pin or "Backprobe" with Sensor CONNECTED to Chassis Connector. If you are getting voltage in (2) but not in this test, then the Sensor or its wiring (between sensor & connector) has an issue.

That's all I know and the "best I can do": The REST is up to you and we await ENLIGHTENMENT.
George
So the live data of the DME showing 0V does not mean the sensor is getting any power, but that the sensor is not sending any power back, thus DME showing 0V for bank1 post cat sensor?


1) I will measure the orangeheater wire on both connectors and compare readings. During my previous bank2 post cat code, during OBD readiness procedure, I was able to get O2 sensor heaters ďreadyĒ. After the contact cleaner, O2 sensor heater will not get ready. I am not sure if that has to do with 0V being sent to the DME and affecting the heater voltage being sent to the sensor...

2) I will drive the car around a few minutes to get to operating temp and look at live voltage of sensors. Iíll measure for voltage at the yellow wire on both connectors. The yellow wire does what?

3) Youíre saying to backprobe the orange wire to see if I am getting voltage while sensor is connected?

Yea, the second screenshots are much more clear.

Can you see/post the fault strategy ISTA shows? Or is the same as this?

Thanks.
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Last edited by Serf27; 01-28-2023 at 02:28 PM..
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      01-28-2023, 01:21 PM   #7
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Before you replace post cat sensor, I suggest check for exhaust leak where the exhaust manifold final pipe connects to the mid pipe of the rest of the exhaust. The bolts and flanges there rust and eventually start to leak. If they are leaking you would find black soot deposits where it leaks. Those two exhaust connections are close to the secondary O2 sensors, so if they leak they effect their readings. Happened to me a few years back, but can't remember what code I had gotten. I didn't not replace the sensor, fixed the leaking connection. Code was only for the secondary sensor though, nothing for first sensor in my case though. Still it is an easy visual check you can do.
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      01-28-2023, 02:31 PM   #8
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Quote:
Originally Posted by PhaseP View Post
Before you replace post cat sensor, I suggest check for exhaust leak where the exhaust manifold final pipe connects to the mid pipe of the rest of the exhaust. The bolts and flanges there rust and eventually start to leak. If they are leaking you would find black soot deposits where it leaks. Those two exhaust connections are close to the secondary O2 sensors, so if they leak they effect their readings. Happened to me a few years back, but can't remember what code I had gotten. I didn't not replace the sensor, fixed the leaking connection. Code was only for the secondary sensor though, nothing for first sensor in my case though. Still it is an easy visual check you can do.
I will probably replace them while I do the testing since Iím already there and will rule out a simple/cheap piece.

The fault strategy I listed does say to check for leaks downstream.
How would a downstream leak after the O2 sensor affect it to the point that it says 0V?
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      01-28-2023, 03:02 PM   #9
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Yeah 0V seems low. I must confess I hadn't read in detail your OP, and not an expert on O2 sensors
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      01-28-2023, 09:21 PM   #10
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Quote:
Originally Posted by Serf27 View Post
So the live data of the DME showing 0V does not mean the sensor is getting any power, but that the sensor is not sending any power back, thus DME showing 0V for bank1 post cat sensor? [see below] ... The yellow wire does what? [see below -- my concept -- may be incorrect]
3) You’re saying to backprobe the orange wire to see if I am getting voltage while sensor is connected? [No, I omitted the Pin#, see below for correction.]
Can you see/post the fault strategy ISTA shows? Or is the same as this? [see below]
Unless I am mistaken in my interpretation of the wiring diagram:
1) the Orange wire Voltage from KL87-Activated fuse will be 12V, but that has NOTHING to do with Sensor "Trim" voltage. Orange heater wire only supplies voltage to the Heating Element, which is activated by the DME completing the ground, ONLY when needed after cold start. That wire is NOT connected to the Sensor Signal circuit in the diagram. Checking Voltage at the Orange wire is ONLY a "Sanity Check", as you have NO Separate code for the Heater Circuit in ANY sensor.

2) The Yellow "Signal" wire from the DME to the Sensor Connector is voltage (unknown if 5V, 12V or what) from DME. As to EXACTLY What the DME is reporting as Pre-cat Sensor Voltage, the only thing that makes sense to me is the RETURN voltage via the Black/Red or Black/Green wires (Bank1 or Bank 2). That is JUST a 2-wire Sensor (if you omit the heater), with voltage in and voltage (as modulated by sensor) OUT.

3) I omitted necessary references in my earlier post regarding WHERE to backprobe or insert Pin. What I SHOULD have said:
I would also measure Voltage (in reference to chassis ground) at X62102/3, Pin #3 of Connector X62102, Black/Red Wire, using a pin or "Backprobe" with Sensor CONNECTED to Chassis Connector. If you are getting voltage in (2) but not in this test, then the Sensor or its wiring (between sensor & connector) has an issue.

4) To "Back-Probe" a connector, with Connection Made, you must properly identify the location of the desired Socket in the Plastic Connector, and then insert a probe attached to Meter into back of connector to make contact with the metal Socket. OR, you can simply stick a pin in the wire, NOT necessarily good practice for O2 Sensor wiring exposed to the elements, and Electrical Tape next to Exhaust manifolds/ Cats, is NOT a good idea.

5) If ISTA can display HOW to Diagnose a particular Fault, WITHOUT being connected to the vehicle that has that fault in Module Fault Memory, I am NOT aware of HOW to do that.

6) I would start with comparing Voltage of the 2 Yellow wires at Sockets #4 of the Two Pre-Cat connectors, X62102 & X62202. ONLY if those are the same do you need to backprobe X62102/3, Black/Red Wire to test Sensor & associated wiring. If there is an issue there, you might consider removing that Sensor from the Exhaust and Inspecting/ Bench-testing for wiring continuity. Always look for burned/ melted wiring that is near Exhaust System.

7) If you have Voltage at X62202/4, but NO voltage at the Yellow wire, X62102/4, then there is a wiring/connector issue between that socket & the DME. Hopefully NOT an issue with the DME itself. If you do NOT have ISTA, feel free to ask for MORE ScreenPrints.

If you find any other omissions, errors or "Mis-conceptions", please advise. This is NOT an area where I have any particular experience, other than trying to interpret wiring diagrams.
George
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      01-28-2023, 09:47 PM   #11
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Quote:
Originally Posted by Serf27 View Post
How would a downstream leak after the O2 sensor affect it to the point that it says 0V?
My not complete understanding of how exhaust leak effects O2 sensor is like this: The post cat sensors are narrow band sensors. They generate a voltage based on the amount of O2 difference between the air inside the exhaust and the air outside of them, the ambient air. When exhaust leaks especially close to the O2 sensor, the 02 percentage around the area outside of the sensor is reduced. Then the sensor incorrectly would report exhaust air has too much O2 in it, because it compares it to now a polluted reference.

I have no idea that that would cause the sensor to report as low as 0V though. Probably not.

Just wrote this to tell that the exhaust leak and 02 sensor interaction is not like intake vacuum leak and MAF sensor interaction.
The exhaust connection where the flanges rust and eventually leak is after the post cat 02 sensors, but it is very close to them, and so can pollute their air around them.
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      01-30-2023, 12:00 AM   #12
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Quote:
Originally Posted by gbalthrop View Post
Unless I am mistaken in my interpretation of the wiring diagram:
1) the Orange wire Voltage from KL87-Activated fuse will be 12V,
IIRC, all 4 O2 sensors are fused to the same fuse, which is shared with the PCV heater?
but that has NOTHING to do with Sensor "Trim" voltage. Orange heater wire only supplies voltage to the Heating Element, which is activated by the DME completing the ground, ONLY when needed after cold start. That wire is NOT connected to the Sensor Signal circuit in the diagram. Checking Voltage at the Orange wire is ONLY a "Sanity Check", as you have NO Separate code for the Heater Circuit in ANY sensor.
Will the orange wire receive power when engine is cold and ACC. on? Or does the car need to be running?


2) The Yellow "Signal" wire from the DME to the Sensor Connector is voltage (unknown if 5V, 12V or what) from DME. As to EXACTLY What the DME is reporting as Pre-cat Sensor Voltage, the only thing that makes sense to me is the RETURN voltage via the Black/Red or Black/Green wires (Bank1 or Bank 2). That is JUST a 2-wire Sensor (if you omit the heater), with voltage in and voltage (as modulated by sensor) OUT.
So the yellow wire sends power to the sensor and the black/red-black/green wires are the ones that send voltage back to the DME? IE: if there is no voltage coming from those wires(when back probed WITH Voltage at yellow wire, the sensor is bad?

3) I omitted necessary references in my earlier post regarding WHERE to backprobe or insert Pin. What I SHOULD have said:
I would also measure Voltage (in reference to chassis ground) at X62102/3, Pin #3 of Connector X62102, Black/Red Wire, using a pin or "Backprobe" with Sensor CONNECTED to Chassis Connector. If you are getting voltage in (2) but not in this test, then the Sensor or its wiring (between sensor & connector) has an issue.

4) To "Back-Probe" a connector, with Connection Made, you must properly identify the location of the desired Socket in the Plastic Connector, and then insert a probe attached to Meter into back of connector to make contact with the metal Socket. OR, you can simply stick a pin in the wire, NOT necessarily good practice for O2 Sensor wiring exposed to the elements, and Electrical Tape next to Exhaust manifolds/ Cats, is NOT a good idea.

5) If ISTA can display HOW to Diagnose a particular Fault, WITHOUT being connected to the vehicle that has that fault in Module Fault Memory, I am NOT aware of HOW to do that.
I have seen someone do this, I am not sure how they did it.

6) I would start with comparing Voltage of the 2 Yellow wires at Sockets #4 of the Two Pre-Cat connectors, X62102 & X62202. ONLY if those are the same do you need to backprobe X62102/3, Black/Red Wire to test Sensor & associated wiring. If there is an issue there, you might consider removing that Sensor from the Exhaust and Inspecting/ Bench-testing for wiring continuity. Always look for burned/ melted wiring that is near Exhaust System.
Why measure at the pre cat sensors if the codes are for post cat? Am I missing something?

7) If you have Voltage at X62202/4, but NO voltage at the Yellow wire, X62102/4, then there is a wiring/connector issue between that socket & the DME. Hopefully NOT an issue with the DME itself. If you do NOT have ISTA, feel free to ask for MORE ScreenPrints.

If you find any other omissions, errors or "Mis-conceptions", please advise. This is NOT an area where I have any particular experience, other than trying to interpret wiring diagrams.
George
This is my plan for tomorrow.

Measure for voltage on Orange/heater wire on Bank2 post cat sensor.

Compare that voltage to bank1 post cat sensor.
If no voltage on bank1 post cat sensor, something is wrong between that yellow wire and the DME or DME has an issue?

If it has voltage cont:
Measure voltage on yellow wire and compare readings between bank1 & bank 2 post cat sensors.

If no voltage on bank1 yellow wire, it is shorted/cut between the connector and DME or DME has an issue?

If voltage is found cont:

Back probe black/green & black/red wires on both banks post cat sensors.
Just to see what return voltage Bank2 (no issues on Bank2 sensor) has and compare that to bank1 return voltage.

If voltage is seen on bank1 post cat black/red & black/green wire, there is a short between the connector and the DME, or DME has an issue?

If no voltage is found on bank1 black/red & black/green wires, the small distance of wire from the sensor to the connector may have a short, or the sensor is bad?

Please advise if I have that planned out correctly or if Iím talking crazyÖ

Thanks.
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      01-30-2023, 12:03 AM   #13
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Quote:
Originally Posted by PhaseP View Post
My not complete understanding of how exhaust leak effects O2 sensor is like this: The post cat sensors are narrow band sensors. They generate a voltage based on the amount of O2 difference between the air inside the exhaust and the air outside of them, the ambient air. When exhaust leaks especially close to the O2 sensor, the 02 percentage around the area outside of the sensor is reduced. Then the sensor incorrectly would report exhaust air has too much O2 in it, because it compares it to now a polluted reference.

I have no idea that that would cause the sensor to report as low as 0V though. Probably not.

Just wrote this to tell that the exhaust leak and 02 sensor interaction is not like intake vacuum leak and MAF sensor interaction.
The exhaust connection where the flanges rust and eventually leak is after the post cat 02 sensors, but it is very close to them, and so can pollute their air around them.
I will inspect that area tomorrow. I did not know a leak downstream of the sensors would cause an issue, as exhaust is flowing downstream. It would be hard for any air to slip into the exhaust and fight its way up to the sensor, but Iíll check it out and do those gaskets.

Oh, how I wish I didnít try to remedy the old code with electrical cleaner!
Big coincidence these codes came after that.

Last edited by Serf27; 01-30-2023 at 11:25 AM..
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      01-30-2023, 09:04 AM   #14
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Quote:
Originally Posted by Serf27 View Post
It would be hard for any air to slip into the exhaust and fight its way up the the sensor, but Iíll check it out and do those gaskets.
It is about the air outside of the exhaust. Those sensors compare the oxygen level that is outside of the exhaust to inside the exhaust. When the air outside of them has exhaust fumes, they will report wrong readings for that reason. That is how exhaust leak affects them. From wikipedia:
https://en.wikipedia.org/wiki/Oxygen_sensor
"The sensor does not actually measure oxygen concentration, but rather the difference between the amount of oxygen in the exhaust gas and the amount of oxygen in air. "
The air mentioned there is the air outside of the exhaust.
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      01-30-2023, 11:53 AM   #15
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Quote:
Originally Posted by PhaseP View Post
It is about the air outside of the exhaust...
"The sensor does not actually measure oxygen concentration, but rather the difference between the amount of oxygen in the exhaust gas and the amount of oxygen in air." The air mentioned there is the air outside of the exhaust.
Where & How does the 4-wire sensor used in N52 engine get this "Reference" reading of oxygen in the "air". I did NOT see any footnote in the Wiki- article that relates to that quoted statement. Many Wiki- articles are good general information, but my "BS Meter" is setoff by this one, which appears to sound like "stone-tablet dictation", with NO source/ authority cited.

Since O2 Sensors have been around for ~ 50 years, there have been CHANGES during that time, and it would be helpful to know specifically HOW Lambda Sensors in N52 work. Quick Google Search yielded mostly advertising ("replace your O2 Sensors whenever CEL comes on" type stuff ;-).

Suffice it to say, that "Reference" explanation differs from anything I have ever heard about O2 sensors. WHERE is the "external" (outside exhaust pipe) "Reference" measurement being made? Do we have to worry about keeping that clean, free of silicone, oil, etc.?

I'll check ISTA & Bentley to see if anything there, and if found, I'll update.
George

Last edited by gbalthrop; 01-30-2023 at 12:22 PM..
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      01-30-2023, 03:14 PM   #16
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Measurements taken from POST CAT CHASSIS connectors.
Cold engine-ACC. ON.

Orange wire on both connectors: ~12V
Yellow wire on both connectors: ~.4V
Gray/white wire on both connectors: ~4V.

4th wire on each connector is a different color: 0V.

I am assuming that is the wire that sends voltage to the DME?

Currently letting the car warm up so I can back probe those 4th wires and compare readings.

IT LOOKS LIKE the DME is functioning properly.
IE: Codes on bank 1 only, though readings are the same in each connector.

Best case, Iím hoping there is a break in that 4th wire that sends readings back to the DME or the sensor is bad.

OBD readiness is now showing all monitors ready, besides the catalyst system.

EDIT- Well now all 4 sensors are showing similar voltage in live data.
Soooo no need to back probe? I might clear the errors and go for a drive.

EDIT- I decided to check voltages before lowering the car. Car is now at operating temperature.
Post cat Bank1 sensor now showed 0V in live data.
I fiddled with the wires and it still showed 0V.
After about a minute, it now (POST CAT BANK1 sensor) shows .1V, then is slowly came up .4V.

Bank2 post cat is showing .6V post cat.
Both Pre cat sensors show 1.8V-1.9V.

Is the sensor weak and unable to produce consistent voltage to send back to the DME?

Last edited by Serf27; 01-30-2023 at 03:43 PM..
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      01-30-2023, 04:30 PM   #17
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Haven't read whole thread fully, but I once had a lambda sensor short internally. From signal to heater power. Was especially confusing at the time because the diagnostic platform (this was on a Vauxhall) would only display upto 4.99V for signal voltage, despite the wire actually being at 12v.

I'm saying this because its not impossible to imagine a signal line internally shorted to heater ground, which would give intermittent 0v, or sensor ground giving permanent 0v.

Ps. The pre cats look to be wideband sensors. They operate differently to be able to interpret not just rich or lean, but how rich or lean. They do this by measuring the current requirement to pump oxygen from one side to the other.

Last edited by Andystobbs; 01-30-2023 at 04:36 PM..
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      01-30-2023, 05:10 PM   #18
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Well, that was unsuccessful.

Cleared codes and Dover around for a bit.
2C32 came back.-Lambda control 2
2CB6 O2 bank 1 post cat signal fixed at lean
2C7E O2 sensor control- Bank1 post cat too rich
2C6B O2 bank1 post cat signal biased/stuck lean.

Cleared the errors and drove some more.

These came up.
2C6A post cat sensors swapped
2CB6
2C6B

Cleared errors and drove.
2CB6 and 2C6B are consistent.
It says bank 1 is stuck lean while also saying itís too rich.
WHAT?

Voltage for sensors going to the DME were steady while driving. Some did drop to 0V when coasting, but came back up when accelerating.

The gaskets where the manifold meets the exhaust system look to be good. No rust on any of those parts.

Here are the fuel trims at idle, on a hot engine.
Fuel Pressure reads 85psi at idle.
Idle is smooth, throttle response is smooth, driving is smooth.
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Last edited by Serf27; 01-30-2023 at 06:47 PM..
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      01-30-2023, 06:10 PM   #19
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Reset fuel adaptations?
Banks 1 and 2 have quite a separation for the ltft. How are the bank 1 injectors
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      01-30-2023, 06:51 PM   #20
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Quote:
Originally Posted by Sgop335 View Post
Reset fuel adaptations?
Banks 1 and 2 have quite a separation for the ltft. How are the bank 1 injectors
In the EKP?

I see an option to factory code the EKP but not reset adaptions.
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      01-30-2023, 07:05 PM   #21
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Oh im thinking mhd, this is not a 335i.
For protool it would be reset adaptations. Not sure why protool doesnt have just fuel adaptations.
Reset adaptations in protool, resets many things and stft doesnt come back unless car goes to sleep and restarted, something like that. I have done it.
But be prepared for that...
Your ltfts are too far as already mentioned
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      01-30-2023, 08:56 PM   #22
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Quote:
Originally Posted by Sgop335 View Post
Oh im thinking mhd, this is not a 335i.
For protool it would be reset adaptations. Not sure why protool doesnt have just fuel adaptations.
Reset adaptations in protool, resets many things and stft doesnt come back unless car goes to sleep and restarted, something like that. I have done it.
But be prepared for that...
Your ltfts are too far as already mentioned
Be prepared for what if adaptions are reset?

The LTFT are far off as in 1 is negative and the other is positive?
Or they are 13% away from each other?

Thanks.
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