Hey,

A few weeks ago I had one of my o2 sensors go bad. The service engine soon light was on, and I checked the code with a mechanic at a dealership I work at. It was a bad o2 sensor, so I ordered the part from Nissan and a mechanic and I replaced the bad o2 sensor with the new one. We reset the light, and it went off.

Tonight, the light came on again. I haven't checked the code yet, but if it is the same o2 sensor, could it mean that there is a bigger problem? This might be worth bringing it to a dealership, no?

If it is the O2 sensor code again, install a ground strap from the head of the affected O2 sensor (right front one, I'll just take a wild guess) and attatch it to the intake manifold where you'll find a couple of other grounds being bolted. Lower intake, I believe.

There have been many a time where a poorly grounded engine has developed bad O2 sensor codes. Replacing the sensor won't fix it, adding grounds will.

Also, double check all of your O2 sensor connectors. They'll all be on the right valve cover. Check them for corrosion and for water intrusion. People that wash their engines have trouble with water getting into the O2 sensor connectors.

Thanks for the quick reply. I will read the code on Monday, and if it is the same o2 sensor, I'll give the ground a try.

the code read P0138: high voltage o2 sensor bank 1, sensor 2.

I reset the code, and it didn't come back on until the other night.

I parked the X in the heated garage at work for a few hours, and when I drove it outside in the cold again, the light turned on. I didn't run the code, just called Nissan and made a service appointment.

Today the light turned off after sitting outside all day. It was warmer out, so maybe that had something to do with it.

Another factor could have been the fuel. I ran it down until the low fuel light came on today (something I try to avoid). The service engine soon light turned off when the fuel got low.

Anyways, can the temperatue outside or the fuel thing make the light go on and off? Nissan told me that they can't see what is wrong with it, or service it, if the light isn't on, so I don't know what to do about the service appointment tomorrow night. Any ideas?

Hi, I’d like to know what happened next. I might have the same problem with my ’01.