2013 continental gt w12 35k miles. check engine and epc light on. pulled codes and found p0234, p0300, p0312, p0305, p1923. checked codes in module 2 found p0300, p0312, p0305. did a smoke test at the vacuum canister and found no leaks. changed spark plugs and coils just to rule it out. and still codes persist. in your experience is the over boost code causing the skip codes or skip causing over boost code? also i have verified if you apply vacuum to the waste gates they actuate with no issues and return. thankyou for any advise

 

We did find it had some bad fuel. when we realized this it had a quarter tank left and we filled it up with fresh and codes stayed gone for a weekend but again. returned.

 

I'm sure someone more knowledgeable will be along shortly but
P0234 is turbo overboost
P0300 is random misfires backed up by
P0312 cylinder 12 misfire
P0305 cylinder 5 misfire

P1923 is for an ECU issue. Given the twin nature of the ECU's I'd be less likely to trust this (assuming that 5 is on a different 'bank' than 12)

Have you cleared the codes and re-tried>?

C

 

The ecu code is labeled in the scanner as see 2nd computer for codes and all ecu2 has is p0305 and p0312 I believe. Using an autel scanner as far as I know should be pretty reliable. Currently chasing down the boost code but not sure if I'm just chasing my tail and I need to be going after miss fire codes instead.

 

Regarding p0234, since a vacuum test on the diaphragm shows that it is functioning the problem is more likely a wastegate solenoid. The wastegate is opened by turbo pressure vented through n274 and n272 solenoids. (FYI usually VAG vehicles refer to the two solenoids as n75). They are located on the right and left side of the engine. Bank 1,right side is easier to get to then the bank2. A bad solenoid or if the solenoid piping is compromised one of the wastegates or both are not opening. The misfires are not causing the overboost. Attached is a diagram of the solenoid locations on a 2013 Bentley. The photograph is the bank1 wastegate solenoid on a Gen.1 Bentley. I believe Gen2 solenoids are located the same as Gen. 1?

Removal of the front end and radiator, for the bank1 solenoid and possible engine removal for bank2.

 

The bank1 solenoid is just above the alternator. The other solenoid is tucked back in that space behind miscellaneous components. This photo is of a Gen1 Bentley for reference.

 

Wastegate would certainly be capable of causing overboost.

C

 

Ended up sending to the Bentley dealer and they replaced the cylinder 12 injector. So far codes have not returned. Not sure how the cyl 5 skip or the over boost plays into it. Thanks for all your help.