GM 8.1 Workhorse O2 Sensors

Mine were P0151 and P0131 codes. I noticed kcgaz said code 202 but I thought maybe he was confused.

In any case the O2 sensor is doing it's job of reporting a problem with the air/fuel mixture and it's burning.

tderonne wrote:
P0202 is NOT an O2 sensor code. Sure that's what they found?

Was thinking the same, that will be injector issues...

P0202 is NOT an O2 sensor code. Sure that's what they found?

I had the exact same problem with my 2004 8.1 engine. I replaced the sensors myself and the problem continued.


I cleaned the MAF and the problem cleared right away and my power increased.

So have them clean the Mass Air Flow Sensor.

It is hard to imagine the 02 sensors are bad at such a low mileage but it is possible to kill them. If someone used the wrong silicone sealant when replacing a part it will continue to contaminate the sensors. Of if there was ever a problem where antifreeze went through the combustion process (head gasket, etc.) it will also foul the sensors. It may even be possible for bad gas to coat them.
You can save a small fortune by replacing them yourself. . They are very inexpensive (the last GM 02's I bought were about $23 at NAPA but that was a while back) and are no more difficult to change than a sparkplug (which is what they're made from).You don't want to push them for too many miles because your only hurting yourself. Long before they fail, they get lazy and don't respond quickly to fuel mixture changes - they don't trip the light until they are very bad although some models trip the light at specific mileages regardless of performance. Fuel efficiency diminishes as well.
Personally, I would go ahead and change them myself.

Rgatijnet, At 90K you wont believe the performance difference you'll feel with fresh sensors.

Happy humbug!
Scott

I have the same 8.1L engine and occasionally it will go in to limp mode or a check engine light will come on. I have a ScanGauge hooked up continuously and monitor several different parameters while I drive. I always clear the codes and usually disconnect the chassis battery with the disconnect switch to reset the ECM. In every case, this has corrected the problem and it may not show up again for several months or several thousand miles.
I have had the O2 sensor code show up and it went away with a reset. I am still on my original O2 sensors and I am now approaching 90,000 miles.
I basically chalk up an occasional check engine light or limp mode as being something temporary that probably tricked a sensor in to thinking there was a real problem. If there was a real problem, a reset would not work and it would quickly show the same code.
Naturally you can replace the O2 sensors if it gives you peace of mind but that does not mean that another temporary problem may show up next time out.