98 Quest - Sensor Question

jantelo · Dec 20th, 2005, 11:04 AM

The check engine light is on. I replaced the knock sensor and then the upper O2 sensor (P0135 error code). I reset check engine light and is back on again giving the same error code P0135. Could be possible that the rear 02 sensor is bad too?? Do you have any other ideas??

spat · Dec 24th, 2005, 08:14 PM

Quote:

Originally Posted by jantelo

The check engine light is on. I replaced the knock sensor and then the upper O2 sensor (P0135 error code). I reset check engine light and is back on again giving the same error code P0135. Could be possible that the rear 02 sensor is bad too?? Do you have any other ideas??

Yeah I get so tired of the myth that the error code means that part is bad!
download the manual here and follow the diagnostic procedure. look for exhaust leaks that may affect air entering or escaping causing an inaccuret reading. also many other possibilities such as worn spark plugs, sticking valves or injectors. the list is a mile long.