I have gotten this code (heat circuit on the RR O2 sensor) intermittently since headers were installed. This lights the "check engine" light. I am afraid this might be a wiring problem (my harness had to be rebuilt and rerouted after being roasted on my SLP headers) but I am reluctant to pull everything apart again before figuring out how much of a problem this is and what the usual cause might be.

Would this code cause an engine malfunction (e.g. make it run rich)? Or can I just reset and ignore? Any expert advice would be appreciated, thanks.


[Modified by rbeckham, 6:38 PM 12/17/2002]

 

ttt :cheers:

 

Robert,
I believe that the HO2S heater circuits are not significant once the exhaust system reaches operating temperature. The PCM checks to see how long it takes the HO2S to transition to operating output voltage on a cold start and if the time is greater than expected, DTC P0135, 0141, 0155 0r 0161 is set depending on which sensor was out of bounds. If the sensors were not functioning at all, you would get additional codes. I had a P0141 right after I installed my FLP's, but it has not returned in 1500 miles. I will email you the pages from my service manual decribing this set of codes and the associated diagnostics. One of the diagnostic aids states that the sensors require a supply of oxygen provided through the wires. If you had wire damage and repair, that might be part of the problem. Or it could be an open heater circuit. Good luck!

Alan :seeya

 

Alan - thanks for taking the trouble to scan these. It makes sense that a failure of the O2 sensor heating circuit should not be a big deal (and I'm not getting any other codes). But why does GM think it's important enough to trigger the check engine light? Also, how does a wire supply oxygen? Strange.

Thanks for your help - Robert

 

Because it effects you emissions before the exhaust warms up.

 

OK - I can see that. Unfortunately, now I am getting Code 0160 instead of 0161 - "circuit insufficient activity." Sounds like it might be as simple as having a dead O2 sensor, though I am concerned about the wiring because of my previous experience of frying the harness. BTW - the car only has about 19K (much of this on the track), and I do still have the cats (but not precats) on the car.

I'll try replacing the two rear sensors and see what happens. Thanks.

 

Both P0160 and P0161 refer to the right rear HO2S sensor. According to the service manual, it could be a bad sensor or the wiring or both. As Alan said the HO2S sensors are supplied with oxygen through the wires.

If it turns out that it is the wiring that is at fault the manual has this to say about HO2S wiring repairs:

Do not solder repairs under any circumstances as this could result in the air reference being blocked.

If the HO2S pigtail wiring, connector, or terminal is damaged the entire oxygen sensor assembly must be replaced.

Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors as they may contaminate the sensor. If the sensor pigtail or harness wires are damaged this could provide a path for foreign materials to enter.

Sharp bends, kinks, etc., could block the reference air path through the lead wire.

Do not remove or defeat the oxygen sensor ground wire (where applicable).

Be sure that the peripheral seal remains intact on the vehicle harness connector to prevent damage due to water intrusion.

The engine harness may be repaired using the J 38125-B terminal repair kit. This kit contains special sealed splices, wire stripping tool, special crimping tool, heat torch, and instruction manual. The sealed splices have the following 2 critical features: Special heat shrink sleeve with sealing adhesive inside and a cross hatched (knurled) core crimp to provide the necessary contact integrity.

 

Bill - thanks, this is a very useful and comprehensive response. The harness repair was done by my dealer, who charged $1200, mostly labor, for this. I would like to believe they followed the book on this, especially since the car was there for three weeks, but I will go back to them armed with your message and try to make certain of this. Regards, Robert