P0012 on a '08 335i

e92Nathanson · 04-19-2021, 06:53 PM

Hey all. Recently picked up a 2008 335i coupe with a 6 speed. Car is running great except for one thing: it's throwing the code P0012 for timing over retarded-bank. The car also occasionally will have a rough idle following a seemingly random drop in rpms when idling at a stop, and the car seems like it's struggling to stay on. Coils, plugs, and injectors have all been done in the past 6 months so I can't imagine it's them, anyone know what this could be/had a similar issue?

N8N · 04-19-2021, 07:46 PM

I'm thinking VANOS solenoids? just logically thinking this through; hopefully someone with high-miles N54 experience will confirm/deny that I'm thinking right. Could also be stretched timing chain in combination with bad VANOS, but that seems unlikely.

RayLivingston · 04-19-2021, 09:15 PM

Almost certainly the intake VANOS solenoid. You can test by swapping the intake and exhaust solenoids. If the fault moves to the exhaust side, the solenoid is bad. Otherwise, it's likely something in the VANOS itself. My experience - if one solenoid goes, the other may well be close behind. I'd just replace both. They're not expensive.

gbalthrop · 04-19-2021, 10:47 PM

What Scan Tool or Diagnostic Software (INPA or ISTA) do you have available?
Can it read Freeze Frame Data (Snapshot of Engine Conditions: Temp, RPM, Load, Cam Angle(?) at the moment Fault Code (P0012) saved?
Can it Display "Live Data", specifically cam angle for both Intake & Exhaust Cam?
What is Cam Angle at hot idle on EACH cam?
When was Oil & Filter last changed & by whom?
Have you inspected the Filter Element and the "Spool" the element is mounted on?

Filter should NOT be collapsed, spool should NOT be missing, and small O-ring should be on lower/small end of spool. Low Oil Pressure at ~ 650 - 700 RPM idle, when oil is hot and less viscous, is common condition for retarded Valve Timing/ VANOS. If you had INPA, you could see Live Data of Setpoint requested by DME and ACTUAL Cam Angle achieved, to see if one or both are somewhat retarded, or LESS than Target Angle. Proper Diagnostic Software reduces/eliminates GUESSING & PART THROWING. PLUS, you could post a ScreenPrint of your INPA Screen here and get advice if NOT sure what values should be.

George

04-19-2021, 06:53 PM	#1
e92Nathanson New Member 4 Rep 21 Posts Drives: 2008 BMW 335i Coupe Join Date: Apr 2021 Location: Baltimore, Maryland iTrader: (0) Garage List 2008 BMW 335i [0.00]	P0012 on a '08 335i Hey all. Recently picked up a 2008 335i coupe with a 6 speed. Car is running great except for one thing: it's throwing the code P0012 for timing over retarded-bank. The car also occasionally will have a rough idle following a seemingly random drop in rpms when idling at a stop, and the car seems like it's struggling to stay on. Coils, plugs, and injectors have all been done in the past 6 months so I can't imagine it's them, anyone know what this could be/had a similar issue?
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04-19-2021, 07:46 PM	#2
N8N Lieutenant Colonel 168 Rep 1,843 Posts Drives: 2009 E92 335i 6MT Join Date: Sep 2012 Location: Berwyn Heights, MD iTrader: (2)	I'm thinking VANOS solenoids? just logically thinking this through; hopefully someone with high-miles N54 experience will confirm/deny that I'm thinking right. Could also be stretched timing chain in combination with bad VANOS, but that seems unlikely.
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04-19-2021, 09:15 PM	#3
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	Almost certainly the intake VANOS solenoid. You can test by swapping the intake and exhaust solenoids. If the fault moves to the exhaust side, the solenoid is bad. Otherwise, it's likely something in the VANOS itself. My experience - if one solenoid goes, the other may well be close behind. I'd just replace both. They're not expensive.
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04-19-2021, 10:47 PM	#4
gbalthrop Brigadier General 2659 Rep 4,010 Posts Drives: 2007 328xi E91 Join Date: May 2017 Location: Fairfax Co, VA iTrader: (0)	What Scan Tool or Diagnostic Software (INPA or ISTA) do you have available? Can it read Freeze Frame Data (Snapshot of Engine Conditions: Temp, RPM, Load, Cam Angle(?) at the moment Fault Code (P0012) saved? Can it Display "Live Data", specifically cam angle for both Intake & Exhaust Cam? What is Cam Angle at hot idle on EACH cam? When was Oil & Filter last changed & by whom? Have you inspected the Filter Element and the "Spool" the element is mounted on? Filter should NOT be collapsed, spool should NOT be missing, and small O-ring should be on lower/small end of spool. Low Oil Pressure at ~ 650 - 700 RPM idle, when oil is hot and less viscous, is common condition for retarded Valve Timing/ VANOS. If you had INPA, you could see Live Data of Setpoint requested by DME and ACTUAL Cam Angle achieved, to see if one or both are somewhat retarded, or LESS than Target Angle. Proper Diagnostic Software reduces/eliminates GUESSING & PART THROWING. PLUS, you could post a ScreenPrint of your INPA Screen here and get advice if NOT sure what values should be. George
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