[gavan_davis]

I have a 2008 E91 N52 with the GM automatic transmission.

Around the end of February, I replaced my intake CPS due to low fuel economy, a CEL, and weird idling. Replacing the sensor fixed all of these issues, but the engine light has been coming and going every couple of weeks since then. There’s never been any misfires, lowered power or limp mode, or any other problems as far as I’m aware. I’ve even tested the battery and alternator and both OBD scans came back “good”.

I’m not exactly sure where to go from here, or if there is anything to worry about. Any help would be appreciated.

The other stored code is for the steering angle position, so unrelated.

[gavan_davis]

Bumping my own thread because it happened again today 🥲

[gbalthrop]

Originally Posted by gavan_davis

... 2008 E91 N52...

If you get P0012 / 2A82 Intake Cam Timing Over-retarded Fault every week or two, then you need to do MORE than just read
Fault Code, or you will simply be "Throwing Parts". Your INNOVA 5010 appears to have a button on right (partially obstructed
in your photo) for "Live Data". Most good Scan Tools can display Live Data of Cam Angle & possibly VANOS Solenoid % function.

See attached INPA ScreenPrint as example of the data which CAN be shown as Live Data. This ScreenPrint was with Warm
Engine, at idle.

So FIRST Step is to read your INNOVA 5010 Manual. download pdf version from INNOVA support site if necessary.
Then see what Live Data of "Valve Gear" or VANOS function your Tool can display. Attach photo of Screen HERE so we
can see what is displayed. ALSO, see if your Tool can display "Freeze Frame Data" which is a "Snapshot" of conditions
at moment Fault Code was saved. Engine conditions such as Temp & RPM, as well as Cam Angles are important for Diagnosis.

There are many possible causes of "Retarded Cam Angle". The DME sends a signal to each VANOS Solenoid for "Target Angle"
of each Cam, Intake or Exhaust. The Solenoid is an Electrically-operated Valve that opens or closes to supply varied Oil
Pressure to VANOS Unit for that Cam. If you have proper Scan Tool/ Software to display (1) Target or Setpoint Angle (sent by DME)
& (2) Actual Cam Angle, you want to see if the Actual Angle tracks the Target angle, which changes with engine Temp/ RPM.

Your Code suggests the Actual Angle is significantly retarded, compared to the Target ("Sollwert") Angle. Causes include:

1) Low oil pressure due to clogged or collapsed Filter element, missing spool or small o-ring, etc.
2) Clogged filter screen in Intake VANOS Solenoid, mounted on front of engine (One on TOP of other -- Exhaust is Lower).

Oil Pressure at idle is necessary to attain proper cam "Advance" via VANOS Unit, and oil pressure is LOWEST at High Engine
Temp (LOW Oil Viscosity), & LOW RPM. So those conditions are MOST Likely to be shown by FF data related to P0012 Fault.
You can remove the Intake VANOS Solenoid & clean screen. If clearly restricted screen, reinstall & view Live data for change.
If NOT clearly clogged, clean & swap with Exh.Solenoid, and see if Fault Code follows part, indicating electrical fault. Make SURE
you connect INTAKE Connector to TOP Solenoid. Label with Tape or such to ensure connectors NOT swapped.
George

[gavan_davis]

This scan tool is not able to read camshaft angle or give values related to the VANOS solenoids. I know my oil filter is in good condition, as I had to replace the OFHG and inspected it then. That was after replacing the CPS and this recurring light started happening. It’s a Mann filter with all the o-rings and only 2k miles on the oil.

I’ll take the intake solenoid out tomorrow since I’ll already have it in the garage to change the rear brakes and brake fluid.

[BRG_N54]

Just wanted to mention there are some VANOS check valves in the head, passenger side near the cooling reservoir, that can get clogged with debris. Might want to check them out also. #7 in this picture:

https://www.realoem.com/bmw/enUS/sho...diagId=11_3735

[gavan_davis]

Thank you, will try looking at that as well

[gavan_davis]

Wow, a lot of life happened since I last responded.

I ended up barrowing an INNOVA 7111 from a coworker and immediately found a fault for the intake VANOS solenoid. I removed and cleaned them throughly with CRC MAF cleaner, inspected the gaskets, the plastic spacers had seen better days but I didn’t have any leaks anyways. Both solenoids and the check valves were very clean before using the MAF cleaner.

This did not remedy my issues, and I ultimately decided to replace the solenoids due to seeing a fault on the same side as the CPS code. Contrary to my normal habits, I did not feel like forking over hundreds of dollars for OEM BMW solenoids. I instead got the URO Parts replacement kit after hearing good things from a couple of friends. After swapping them out, I reconnected the battery, cleared the CPS code, and let the car idle for about five minutes before going on a gentle drive around downtown for all the stop and go traffic, and later some open roads. I was attempting to re-create the issue of decelerating and coming to a stop and having the engine bog down and fluctuate rpm for a few seconds once stopped. This did not occur, and it also hasn’t had rough starts since changing them. The car genuinely does feel a bit smoother, especially lower in the rpms.

Thank you all for your help and suggestions 😁

[gavan_davis]

PS,

From a diagnostics standpoint, I definitely should’ve tried swapping the solenoids around and seeing if the code followed. This escaped my mind, but it is what it is as of now 🤷‍♂️