CEL for o2 sensor, replaced sensor. still have the codes!

[brrrnntsshhhh]

Hello This is on my 98 galant (n/t) that was throwing codes P0141 (heated oxygen sensor bank 1 sensor 2) and P0136 (Heated oxygen sensor h02s sensor circuit fault). I replaced the o2 sensor before the cat with a BOSCH universal sensor in order to get my car ready for emissions. Unplug the neg battery terminal, install sensor, hook everything back up. car starts up, no code - drive it to emissions, car drops rpms and feels like going to stall out when slowing down / idle for lights. still no CEL. get to emissions they turn car off and back on, light comes up. I unplug sensor, recheck my wiring make sure everything is secure. it did appear like one of the wires wasn't connected completely, secured it and reinstalled. Same issue, car doesn't throw the light until it is turned off and back on.

any idea on how to fix this? I checked the wiring near the ecu and it all looks fine. should i try installing a specific sensor versus the universal one? or is this likely to be a more complicated wiring problem

 

[wrencher]

Those universal o2's are not the greatest IMO.
I never use them too many problems.

What code came back?
As for the o2 heaters, is there 12 volts @ the o2 sensors on the red wire on each sensor?

 

[brrrnntsshhhh]

do you think it is a faulty sensor?

Hmm i havn't tested that yet but will try it, does the car need to be on or just the battery plugged in?

 

[wrencher]

I will not use universal's on customer's car ever. I'm not doing them any favors by trying to save a few bucks on one.

The key has to be on to test for power coming to the o2 sensor.
12 volts or very near it on the red wire coming into the o2 sensor.
The PCM/ECU grounds the heater to turn it on, testing that section of the circuit requires a little more specialized testing.
Not sure exactly what the ECU is looking for on this particular vehicle, but likely amperage draw on the o2 heater . I'd have to look it up by MY & engine.
You can ohm out the heater also in the o2 sensor. Usually they are under 5-6 ohms.
Another spec I'd have to confirm, changes vehicle to vehicle.

Have you confirmed what code returned?

 

[jpmxrider489]

I would try to replace the cat. I think that will fix it. Is all your vacume lines hooked up correctly?

 

[brrrnntsshhhh]

I would try to replace the cat. I think that will fix it. Is all your vacume lines hooked up correctly?

the sensor is before the cat, havn't checked the vacum lines but will do.

I will not use universal's on customer's car ever. I'm not doing them any favors by trying to save a few bucks on one.

...

Have you confirmed what code returned?

thanks guys for the quick replies!
I already soldered the wires and then went back and confirmed the same codes were being thrown. Just pulled off the sensor and going to try and exchange it for a model specific one or if they will give me any kind of credit towards one. i know it will be a few days before it comes in though

coincidentally my water pump just went out as well
this is going to be a fun weekend

 

[doubleclutch]

Just found this thread and I have the same issue.

Is anyone going to tell him that those codes are for the REAR sensor not the front one?

I did replace the rear sensor and I still have those codes. I understand the one is for not having a cat (I have a very small cat it may not be doing the job) but the code for the heater circuit makes no sense to me. Any ideas?