I've been dealing with issues with a CEL for a while now. Rough Idle, Mixture too lean, too rich and a P1297 (Connection turbocharger - throttle valve pressure hose). I changed out my MAF sensor and that got rid of everything but the p1297 which indicates probable boost leak. Been working my way through the hoses and can't find anything. My car ended up at the mechanic for another unrelated problem and I put them to work on that last code. On a fluke they put a different used MAF sensor in and the car works perfect. Do I have an oddball situation here or is it possible for a bad MAF sensor to cause the car to idle rough and throw a p1297 code?

BF

 

^it could be that they reset the ECU at the same time (likely) and the code was cleared... I would ask if they simply swapped the MAF or swapped it and either purged the learned data from the ECU via VAG COM or hard reset...

 

When I changed the MAF I did reset the codes in the ECU (scan tool several times, Disconnecting battery for several hours another). Would a vag com do something different?

 

not to my knowledge

 

yes a vag would help you out...
just recheck your fittings and sure everything is tight.
do u have a boost gage? if so what are you reading?

 

^ if he's asking if a vagcom will reset in a different way than manually unplugging the battery, then i don't think so...

 

I was reading aprox 11-12psi in boost when accel from a dead stop, but the car would throw a p1297 code within about 3 minutes. I have taken every boost hose off and put them back on with no luck correcting a suspected leak. I've done several pressure tests with no luck finding a leak. Now with no other changes _other_ than swapping the MAF sensor my mechanic was able to boost to 14psi with no codes popping up for several hours of driving. I've tried contacting the place I got my MAF sensor from to inquire about a replacement, but haven't gotten a reply yet.

BF

 

^was it a brand new MAF, or used?