well ive installed both new o2 sensors in my car within the last 2 weeks installed the one after the cat yesterday and i got P140 (02 sensor ckt no activity bank 1 sensor 2) Obviously the heated o2 sensor ive double checked everything it was a direct oe plug in one so i dont know why that one anyway i reset it.

While going to work today i get another cel it i thought it would be the P140 again. but when i scanned it it came up at P0172 (System too rich)

Any ideas what i could check for these are there any fuses ect?.. or do these go hand in hand any suggestions are apprciated

i dont understand the first part of the post but here's my 2 cents.

when you get a 02 code, its usually telling you that the car is running too rich or too lean. If your car isn't runing rich or lean, than the sensor is faulty. 02 sensors dont usually go out tho. you have to figure out what is causing your car to run too rich.

it can be things like a leaky injecter, fuel issue or evap canister purge stuck open. could be anything.

You should find out what the problem is quick cus the longer the run your car running rich, the more chance you taking on clogging up your cat convertor and that repair can be expensive.



2003 Cavalier 2dr. 5spd

drivemybrosZ24 is right. Sounds like an EVAP problem that is fouling the 02 sensors. An EVAP cannister that is saturated will cause rich conditions, fuel in the vac lines also causes rich conditions. Worn cam, intake or exhaust valves? Could be anything.

so is there anyway to tell for sure? the car has 171k miles on original engine it could be anything. IF i hook it up to tech 2 will it tell me more of why its rich ect?

basically i keep getting o2 sensor no activity.. OR BOTH along with system too rich

Best thing to do is bring it in and get it hooked up to an On-Board Diagnostics Systems Scanner. They can read the Fuel Trim System and see whats going on