Alright I am no mechanic by far but this forum has helped me out alot by talking to a friend of mine that work on my car. My mechanic just changed the knock sensor after I received the code from autozone and his OBDII reader. My mechanic states he cleared the code after replacing the knock sensor and harness but received another code pertaining to a bank 1 back lean and he received a new code for the throttle.

Could I have now just a vacuum leak in my 2003 g35 coupe or do I need to have him check the MAF? Where should he start?

 

You need an OBD code reader/"scanner"

No one on here knows what is wrong until you tell us exactly what code it is.

Give us some more info. Autozone and Advance Auto Parts read the codes for free.

 

Sorry about that here were the codes prior to the knock sensor being replaced. P0327 and P0174 now after replacing the knock sensor my mechanic before he cleared the codes got p0113 IAt circuit, P0223 throttle position, P0123A throttle position, on top of the P0327 and P0174. Today when we checked for the codes we only got Po174 system too lean bank 2. The car went a week and a half before the light came back on again approximately 328 miles. My mechanic is thinking the lower intake gaskets need to be replaced based on his observation after replacing the knock sensors. Could this be the case? The car drives fine without any problems but this check engine light is starting to annoy me.

 

Help me out here guys if I am going in the right direction for a Po174 code. After doing some research if it is the intake gaskets I should do a smoke test? Second, rotate the 02 sensors and if the code changes to the opposite bank of the sensor change then that is the problem? Am I missing another cause for a lean bank po174 code?