Mister Bally

For about a month, I would get the CEL to light within a minute or two whenever starting my '04 with 4.2 BFM engine. Whether a cold start or re start after stopping for a bit with a hot engine. Never a performance issue, just a pesky yellow light.

I carry a scan tool so I can easily clear the fault(s) and the light would always stay off for the duration of the drive. Even did a couple 200+ mike trips and no CEL.

Codes are P0020 Intake Camshaft Position Actuator Circuit/Open Bank 2 and
P0022 Intake Camshaft Position Timing Over-Retarded (Bank 2). Yes, codes were the same with Ross-Tech VCDS and the scan tool.

Whever I would reset at Idle, the engine RPM's would increase a bit, maybe 100 RPM's, just enough to notice. Reading what little I could find on the Ross-Tech site and Bentley manuals the information said this problem barely affects performance. But the light on really bugged me.

The Bank 2 sensor is at the back of the driver's side cylinder head. The Bank 1 sensor is at the front of the passenger side head (North America applications). SInce the sensors are identical, I swapped them. The Bank 2 sensor is a pita to remove but it can be done (two bolts with Loc-Tite). I wanted to see the fault code change to the Bank 1 sensor before spending $150.00 on a replacement sensor. Also, I noticed some white dust on the face of the internal Hall-effect sensor so I wiped it clean. After the swap, the problem has not reappeared in five days so I'm attributing the fix on the white dust on the sensor/encoder.

Just an FYI in case others ever run into this.I thought if the sensor was truly bad, the code shoul come back sometime during a longer trip. Must be the slower rotation upon start-up and a delay in illuminating the light. Who knows?

mishar

Could it be just a bad connection?

Mister Bally

No, but a good thought. Connectors were firmly installed, clipped down tight and no corrosion on any terminals.

MP4.2+6.0

Right diagnostics, frugal approach and assessment.

From having pulled and rebuilt a head on my A6 4.2, yes things are actually basically identical as you concluded, but sometimes rotated front to back like the position sensors to deal w/ the 180 degree head casting rotation to tie in to the manifolds.

pfishwacker

Did you ever figure out your issue? My '04 A8L 4.2 just started having the same problem - when the outside air temp dropped to 7degrees F. I have not noticed a rough idle, but have noticed slightly higher idle.