98 Z28 A4 - 62,000 miles. second tim e this code tripped and I believe the last time was about 8000 miles or so. THEN I was told no big deal if everything seems OK and it did, still does with one exception : I hear a slight ticking on cold start around the drivers side engine.
Anyway - now the code P0442 - EVAC/O2 Sensor/Lean Fuel 1 & 2 comes up again. AUTOZONE guy says it could be VAC lines or PUMP and if ignored could score a PISTON.

I searched and did not find a definitive opinion and would appreciate why this keeps tripping this code. I NEVER fill th gas while engine still running like somebody said and take very good care of this Z28, garage kept, the whole nine yards.

 

by the way, after more searching here at Z28.com, I saw a guy boosting and tripped this code, NEVER has any nitrous been used on this Z. normally I fill up at half a tank but this time the fule gague went pretty low, possible that could have effected this?

 

does any of this help

sounds like maybe a bad sensor

 

I have seen the p0442 and p0440 come up on a number of GM vehicles. From past experience, nine times out of ten, it is caused by a loose or defective gas cap, which acts as a leak in the evap system.

Clear the code, make sure the cap is tight, or until it clicks at least three times and see what happens.

this code will only set on cold start btw.

good luck.

 

Go for the gas cap not sealing first. If you keep getting P0442 consistently you've probably got a small leak in the EVAP system somewhere - friend of mine found his by having a shop inject smoke/pressurizing the system.