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      08-20-2020, 02:02 PM   #1
Pruzina
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Please help P0492

Please somebody help me.
Hi I'm trying to solve my CEL. Code P0492 Secondary Air Injection System Insufficient Flow Bank 2.

E93 328i SULEV 2007. Unfortunately can't go to dealer for warranty repair as it has 190k miles.

I took it apart and checked everything. Actually already like 10 times.
Filter + box intact and ok
Hose and connections ok
Check valve NEW works as should
Pump works as should (always turns on for half a minute during cold start)
Ports in the head are okay. Checked with multiple methods.

Cleared the code came up every single time.

Everything seems to work as should. I watched all YT videos read all posts didn't find anything.

As it's throwing code for bank 2 only, it looks like the pumping system it self works properly.

Could it be O2 sensor in bank 2? But not getting any other O2 sensor related codes.

Also downstream O2 sensors are not active while the pump is running bcs they are still too cold. So based on what data is P0492? Upstream O2 sensor? Bcs what else could measure the air flow?

Pls any idea would help. I’ve spend so many hours tracing this with no success. And really not planing to pay dealer $200/hr.

Last edited by Pruzina; 12-08-2020 at 10:59 PM..
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      12-08-2020, 10:22 PM   #2
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Pls help
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      08-05-2021, 03:57 PM   #3
bvoyer
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I am getting same code

How can I figure out the P0492 repair when there are about 10 different things it could be? Visual inspection showed nothing, pulled 40A fuse in glove compartment and it looks ok, where is the relay located?
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      08-05-2021, 03:59 PM   #4
bvoyer
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P0492

The car has been running rough for the last year or so, it seems to kick into acceleration every once and a while. The service engine soon light comes on and goes off randomly so I thought it was just scheduled service but now it failed the state inspection.
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      08-05-2021, 04:00 PM   #5
bvoyer
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P0492 Fuse or Relay

Could it be as simple as the fuse or relay or would the popping while accelerating be more like the secondary air injection pump?
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      08-05-2021, 04:39 PM   #6
gbalthrop
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Quote:
Originally Posted by bvoyer View Post
How can I figure out the P0492 repair when there are about 10 different
things it could be? Visual inspection showed nothing, pulled 40A fuse in glove compartment and it looks ok,
where is the relay located?
You don't say what your build Month/Year is, but attached are ISTA ScreenPrints of Secondary Air System.
These show Fuses, Wiring Diagram, and Relay Location in Front of E-box, outboard Relay of TWO.

You can download a pdf version of Bentley Manual from the link provided in the attached pdf, E9x References, 210523 Revision.
At pages 130-12 & 130-13 (pp. 265-266 of pdf) you will find information about the Secondary Air System.

If you post back, please indicate your build date and/or Last-7 Characters of VIN, along with what Diagnostic
Software, INPA/ISTA, or Scan Tool you have, AND what Fault Codes, Definitions & Details are read.
George
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File Type: pdf E9x References 210523 Revision.pdf (235.9 KB, 174 views)
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      08-05-2021, 04:45 PM   #7
bvoyer
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P0492 need to fix ASAP

Please help!
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      08-05-2021, 04:50 PM   #8
bvoyer
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Thanks George

The shop where I had my car inspected used an iPad type of reader and put in some numbers at the bottom of drivers door, not sure if that helps, so all I have is the P0492 code. My car is a 2009 328i xDrive and last 7 characters of VIN are A511302
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      08-05-2021, 05:26 PM   #9
gbalthrop
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The ISTA ScreenPrints and info I attached to prior post are CORRECT for your VIN (your vehicle is a 2009 model built November, 2008).

I would begin by testing Fuse F16 (Electrically), as well as F89. See attached Fuse Charts from Bentley for location of F16 & F89.
All E9x models built AFTER 9/1/2007 (2008 & Later Models) have SAME fuse Layout at the JB FuseBox.
Then I would get the Fault Codes read at Advance Auto or Autozone (free service). Photos of Scan Tool Screens posted here.
We can then suggest other tests you can do, such as opening E-box and using multimeter to test Relay.
If you have a Windows 10 Laptop, consider getting K+DCAN Cable ($45 from BimmerGeeks), and
FREE Download of INPA and ISTA Diagnostic Software. You can then Diagnose It Yourself.

Let us know if you need suggestions on what to test & HOW.
George
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      08-05-2021, 05:51 PM   #10
bvoyer
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I will start with that

Thanks for the info
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      08-06-2021, 06:59 AM   #11
bvoyer
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New fuses

I changed out F16 and F89. I am also attaching the read from Advance Auto. I haven't driven around much so I'm not sure if it did the trick, but how long should I wait for the light to go off?
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      08-08-2021, 06:21 AM   #12
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Passed inspection

The SES light went off after changing fuses, not sure if it is really fixed but car passed and all set for now. Thank you
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      08-08-2021, 09:15 PM   #13
Pruzina
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SOLVED: one of the ports in the head was partially clogged, it had some flow but not enough.
Ended up buying another check valve cut the top portion off blocked working port and repeatedly filled with B12 chemtrol.
Worked perfectly.

Recently used same method on friends MB ML350 and worked as well.
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      02-05-2022, 06:03 PM   #14
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I had the same problem with a 2008, 328i, SULEV N51 engine with 296,000 miles. In my case, the code was P0492 (applies to cylinders 4,5, and 6). Bought an old valve off eBay, removed the top and used the bottom to pour B12 Chemtool liquid. I created a metal gasket to block the liquid from going into the front side of the engine. Since the rear passages were fully blocked, I just filled the valve with B12 juice and kept it filled for a few days, occasionally pushing the liquid with a 100 PSI air-hose. After a few days and the blockage still present, reassembled the original valve and hose and tried to start it. It took two days of repeated attempts to start until eventually some liquid came off the tail pipe and started. Took it for a fast run on the freeway and eventually the computer cleared the permanent code that had been set over the last two years.
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      10-15-2022, 03:17 PM   #15
chico2522
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HI! Any chance you can post a pic of the valve you cut? How did you do it. I have a 2011 n51 that has a bank 1 insufficient flow problem. It even burns the plastic air line from the Secondary air pump! its had this problem for 4 years!
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      10-15-2022, 06:45 PM   #16
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Quote:
Originally Posted by TeSmSp View Post
I had the same problem with a 2008, 328i, SULEV N51 engine with 296,000 miles. In my case, the code was P0492 (applies to cylinders 4,5, and 6). Bought an old valve off eBay, removed the top and used the bottom to pour B12 Chemtool liquid. I created a metal gasket to block the liquid from going into the front side of the engine. Since the rear passages were fully blocked, I just filled the valve with B12 juice and kept it filled for a few days, occasionally pushing the liquid with a 100 PSI air-hose. After a few days and the blockage still present, reassembled the original valve and hose and tried to start it. It took two days of repeated attempts to start until eventually some liquid came off the tail pipe and started. Took it for a fast run on the freeway and eventually the computer cleared the permanent code that had been set over the last two years.
any chance you have a picm on how you cut it?
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      10-16-2022, 01:27 PM   #17
Pruzina
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If you cut the top part you'll be able to control the valve with your hand. Bolt the piece on the block and squirt some solvent inside through the side opening. Also block one of the ports if you have clogged only one.
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      10-19-2022, 04:16 PM   #18
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Quote:
Originally Posted by Pruzina View Post
If you cut the top part you'll be able to control the valve with your hand. Bolt the piece on the block and squirt some solvent inside through the side opening. Also block one of the ports if you have clogged only one.
ok! thank you! just curious, what did you use to block the port? tape? aluminum foil? cant wait to try cause like i said i have this problem for more than 4 years! Also, did you car by any chance burn the plastic air line that connect to the side of this valve?
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      10-19-2022, 04:22 PM   #19
Pruzina
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I used aluminum foil folded to make 2 or 4 layers not sure. You got to block the good port to avoid all liquid flowing right through and not working on the blockage.

I was actually thinking why is your plastic line melted. Does it looks like it's melted from outside heat or inside?
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      10-20-2022, 11:44 AM   #20
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Quote:
Originally Posted by Pruzina View Post
I used aluminum foil folded to make 2 or 4 layers not sure. You got to block the good port to avoid all liquid flowing right through and not working on the blockage.

I was actually thinking why is your plastic line melted. Does it looks like it's melted from outside heat or inside?
Yeah its strange. It happens when the secondary air system is on but I accelerate. Thats the only time the line burns. if i let the system finish nothing happens to the line.
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      11-04-2022, 11:41 AM   #21
Pruzina
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You should wait until the pump stops before you start driving. It's running 30 sec max and it's actually good practice wait half a minute to let the engine lubricate properly before you move. It will be good for all parts of your engine.
Clearly the hot exhaust gas entering through the valve your plastic pipe.
I would probably start with replacing the valve bcs I don't think that should be happening. You may not even have the ports clogged just the valve doesn't work properly thus not letting the air from the pump enter your exhaust system setting your check engine light.
I may be wrong but this is the easiest and cheapest way to start.
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      11-05-2022, 01:33 PM   #22
chico2522
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Quote:
Originally Posted by Pruzina View Post
You should wait until the pump stops before you start driving. It's running 30 sec max and it's actually good practice wait half a minute to let the engine lubricate properly before you move. It will be good for all parts of your engine.
Clearly the hot exhaust gas entering through the valve your plastic pipe.
I would probably start with replacing the valve bcs I don't think that should be happening. You may not even have the ports clogged just the valve doesn't work properly thus not letting the air from the pump enter your exhaust system setting your check engine light.
I may be wrong but this is the easiest and cheapest way to start.
i believe you're right and will change the valve. and im hoping thats something clogged but i did the procedure and so far the lights come back on after ussing 2 cans of b12. i just tried again and used 4 cans of b12 so will see if maybe that does it. If not im at a loss and will maybe check the fuses again.
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