P1287, P0393, P0391, P1073 faults System too lean at idle bank 1/2

[P T]

 

Not able to understand what could have caused these fault in 08 Cayenne Base. Please guide me on how to further investigate this

[JFP in PA]

Overly lean conditions come from a couple of issues: insufficient fuel (low pressure or volume flow, plugged injectors), or intake vacuum leaks allowing too much air into the combustion process.  As it seems to be on both banks, I would be looking at testing the fuel delivery system, or smoke testing the intake system looking for leaks.  With the high idle fault, it is most likely a vacuum leak.

[P T]

There was a vacuum leak. Break booster hose was split, have replaced it. System too lean codes have cleared but below two codes(P1073 and P1057) have persisted

 

 

Please advise how to solve this.

[JFP in PA]

Make note of the codes and clear them.  They may not return and have been caused by the vacuum leak; only some driving will tell you.

[P T]

Tried clearing the codes 4 times, but P1057 and P1073 keep coming back after driving some miles. Any insight on how to check this issue would be helpful.