O2 Code

[GCNTSi]

My O2 code occasionally comes on, when the car is fully warmed up, and the car runs like crap when it does. Can they be cleaned or should I replace it. I just rather not replace it since it's only about 6 months old.

 

-GCNTSi.

[mikec]

Usually having the O2 code pop up while driving is a result of some OTHER fuel system problem if the car runs poorly. Normally a StarQuest runs a bit rich until the O2 sensor is working; when they get old or weak often they'll quit reading during sustained highway cruise (low exhaust temps) and the O2 sensor code will reappear - yet the car continues to run fine. Without the LED or other light, most drivers would never know the error code is popping on and off because they don't feel any change in the way the car runs.

 

What you're describing is more like an O2 sensor that reads low output for a while (that's what sets the ECU error code) due to running very lean or very rich (=cold exhaust). Typical causes are:

* injectors with dirty electrical contacts or bad electrical connectors (aka "injector clips")

* dying injectors

* fuel starvation from a dying fuel pump or blocked pick-up screen inside the fuel tank or blocked "cone" filter in hose from tank to fuel pump or blocked main fuel filter.

 

Dying fuel pumps often work well enough when physically cold but as they heat up they can't flow enough fuel to satisfy the engine. A fuel pressure guage, tapped into the hose from the fuel filter to the t-body or, more commonly, screwed into the top/rear of the t-body where the hex plug is will tell you a LOT about the system. Idle fuel pressure is one thing... but what is the fuel pressure while driving after a bit and trying to accelerate? THAT'S when a fuel pressure guage is valuable. You can use washers to lift one corner of the hood (on the hood hinges) and tape the guage to the windshield wiper area for the test drive.

 

mike c.

[GCNTSi]

Thanks mike c, the fuel pump is slowly failing, so I guess that's the problem. I'll know for sure once the new one comes in, probably next week.

 

Thanks,

-GCNTSi.