Like they say, save you're money, it MIGHT be worth something some day.

 

Not in this decade lol

 

I have a 91 & a 92 and would like to clarify.

This secondary O2 sensor is only on the 97+'s?
I'm currently throwing codes
17 low engine temp
21 no signal from O2
51 lean mixture detected

And now considering what I've read I'm thinking my jacked up thermostat may be the cause of the whole problem! Good thing it's easy to swap them out.

 

It's in 96+ because that's when they started with the OBD2 diagnostics system. no signal from O2 can mean there's a bad electrical connection or the sensor itself is shot. I'd grab one from the junkyard and see if it changes anything.

 

I put in a new o2 sensor and am still getting the same codes. I read on another post that the running cold doesn't allow the o2 sensor to hit the 600* that it needs to turn send the right signal.

 

The codes need to be cleared......I believe disconnecting the battery for a few minutes accomplishes this. The O2 sensors have a built-in heating element and will usually heat up in less than a minute and send info to the computer.

 

I cleared the codes and they came back with the new O2 sensor installed! Changed the thermostat today, so now I have the proper operating temps. Will check tomorrow to hopefully see the codes are all gone.

The problem why my O2 sensor wouldn't get warm enough is because the engine max temp has been 100* for the last few weeks since it's been cold.

 

Are your O2's not heated? The heated ones will light off very quickly, well before coolant temp reaches 100F. Sounds like other problems maybe.

 

I GOT A SIMILAR PROBLEM! i replaced ALL 4 02's on my 01 and every time i clear the codes a couple weeks or so later it comes back. any one heard of any computer problems that might affect the 02's?