P0018 Pending

[michael.williams1]

I have a pending DTC that keeps appearing every now and then, suggesting there’s something intermittent happening with the cam timing on Bank 2. I thought I’d investigate further by a) replacing the cam sensor (as they’re not that expensive) and b) pulling the cam actuator to test and clean it. The engine oil last was changed in May this year but, prior to that, it hadn’t been changed for 4 years. I’m wondering if the last change may have flushed out some sludge / contaminants and particles are accumulating in the cam actuator, affecting it now and again(?). The car drives fine and I don't have a CEL coming on.

Please share any experiences of dealing with this issue, as they may help. In the research I've done it often seems to be the cam actuator that turn out to be the problem …

 

[michael.williams1]

Update: I've now changed the engine oil and filter, replaced the cam position sensor and removed and cleaned the cam actuator but the pending fault still appears occasionally. I think it only comes on when the car is warming up / when the viscosity of the oil hasn't thinned, which I suppose could slow the action of the cam actuator and VVT mechanism(?). I've also sent the engine oil off for analysis so I will see what if anything that reveals and take it from there. I may replace the cam actuator but it's £150 for the OEM part and the car drives absolutely fine with no CEL appearing. Perhaps there are other cars out there that have this anomaly but the owners remain completely unaware of it ...

 

[malarcy]

FYI - this is the diagnostic "detail" for that code - measured against your findings so far, your "next steps" seem sensible - but personally I would monitor and be prepared to fix if it becomes an active fault.

 

[ianthow]

If it was the variocam solenoid, you would expect rough running at certain speeds and codes for an intermittent misfire on each cylinder on that bank. In the absence of these, the "permanent deviation" suggests timing chain or tensioner issues on that bank.

 

[michael.williams1]

If it was the variocam solenoid, you would expect rough running at certain speeds and codes for an intermittent misfire on each cylinder on that bank. In the absence of these, the "permanent deviation" suggests timing chain or tensioner issues on that bank.

There isn't a permanent deviation; it only ever logs as a pending fault and that's quite intermittent. The car didn't get an oil change in the 4 years before I bought it and during that time it was very lightly used. I reckon the cam actuators could get a bit sticky after that, and I think that could be causing the pending P0018 because the pulse width modulation from the DME doesn't overcome this quite quickly enough so there's a slight momentary imbalance between one bank and the other. If I rev the car in neutral I reckon I can detect this around 1500 rpm where the actuators start to pump oil through to the cam phasers and one bank is slightly out of balance with the other. This may fix itself by just driving the car, but if not I think I'll try a new actuator as a next step. Unfortunately I don't have the PIWIS or Duramatic diagnostics to look for Cam angle differences between Banks. I only have iCarsoft POR2 which just shows overall ignition advance.

 

[malarcy]

I often find these kind of codes lurking in cars that I have scanned / worked on for folks - some cars just seem to have a "sensitive spot" for something falling outside the spec for a particular component.

If it's not causing a running issue and you are not getting a dash warning then its a case of "the more you look the more you find". Even if it turned into an error chances are 1st pass at the dealers would be "clear the code and see if it comes back".

With you on checking and the inquisitive mind will always work towards a cause and a remedy - but i feel you may well be chasing a ghost here.