Heated O2 Sensor Readings?

[EddieC]

I chased down why our remote start system was not functioning and as someone advised it was the CEL that related to one of the O2 sensors (Bank 1 position 2, downstream drivers side). I swapped in a new oem sensor, cleared the code and cured the remote start issue. Unfortunately after about 30 miles the CE light is back on.

I ran a "live" operating scan report on the O2 sensors and that same one has different mV report than the other 3. The other 3 vary but much of the time are around 750 mV. The questionable one is steady around 450 mV.

Is that a problem and if so what could be causing it?

I rechecked the connector and the new connection plug is securely in there. The only thing replaced was that sensor and it's attached wires/plug.
I don't see nibbling on the wires but it is an inconvienance spot to be peering into.

 

[Dustin Jackson]

@EddieC I have heard there are O2 sensors to not use, this might be the case

 

[CaptainAmerica1]

Or maybe the fuel trims are getting adjusted back to where they need to be and it just takes a bit to dial it in…

 

[Fless]

Is the heater circuit working? Got voltage on the two heater pins and will it light up a taillight bulb as a test load?

 

[EddieC]

Is the heater circuit working? Got voltage on the two heater pins and will it light up a taillight bulb as a test load?

Which would those be?

 

[EddieC]

@EddieC I have heard there are O2 sensors to not use, this might be the case

Not to use? It was GM oem used for replacement.

 

[Fless]

Which would those be?

The two heavier wires that go to the sensor. They should be the same color.

This might be of interest:

 

[Foggy]

Once the engine is warmed your upstream O2 sensors will bounce up and down.
Anywhere from 0 mv up to 999 mv. and they bounce constantly. If the output is NOT
bouncing, it's not working

 

[Fless]

You'll obviously have the code for that side. If you go to the trouble to swap those downstream sensors side to side, see if the code moves to the other side.

 

[EddieC]

Once the engine is warmed your upstream O2 sensors will bounce up and down.
Anywhere from 0 mv up to 999 mv. and they bounce constantly. If the output is NOT
bouncing, it's not working

Yes, both upstreams are bouncing from about 50 up to 750+

 

[EddieC]

The two heavier wires that go to the sensor. They should be the same color.

This might be of interest:

Moral of the video is go for the obvious first; don't trust the new part.

 

[EddieC]

You'll obviously have the code for that side. If you go to the trouble to swap those downstream sensors side to side, see if the code moves to the other side.

Suggestion noted.
How long would it take to throw a code?
As I mentioned, I drove a bit after replacing the original suspected O2 sensor before get the code back.
I reset it again today after rechecking the connector and drove it about 10 minutes and so far no code but I expect it might be back.; tomorrow will tell.
Perhaps a partly faulty replacement the works for a while before it sends a code?

 

[Foggy]

It will take at minimum 1 full drive cycle.. Now that "cycle" will have to be varied
driving at at least 50 mph at some point...
Give it a bit and see if it comes back..
Just want to make sure also that you are replacing the correct O2 sensor.
Bank 1 is drivers side. Bank 2 is passenger side.

 

[EddieC]

It will take at minimum 1 full drive cycle.. Now that "cycle" will have to be varied
driving at at least 50 mph at some point...
Give it a bit and see if it comes back..
Just want to make sure also that you are replacing the correct O2 sensor.
Bank 1 is drivers side. Bank 2 is passenger side.

After resetting the light yesterday, wife made a short trip to the grocery store this morning and light was back on when she got back.
I warmed it up in the driveway for about 15 minutes after another reset then took a 25 mile ride, including a short stop in the middle, with speed as you noted and no warning light. And yes, doing the correct one. Fingers Crossed but ready to put in more effort as many suggest if needs be.

 

[EddieC]

Well, we got 40 miles in 2 days and the light is back on. Same O2 sensor (bank 1 position 2) but instead of lean now it threw a rich error. What a PIA. I want my remote start function to work now that it's winter and snowed yesterday. Fortunately it doesn't affect drivability.

 

[EddieC]

Once the engine is warmed your upstream O2 sensors will bounce up and down.
Anywhere from 0 mv up to 999 mv. and they bounce constantly. If the output is NOT
bouncing, it's not working

Errors are on a downstream sensor.

 

[EddieC]

The two heavier wires that go to the sensor. They should be the same color.

This might be of interest:

My 4 wires from the sensor to the plug appear to all be the same size but there are 2 of the same color; white.

 

[Just Fishing]

I have seen where a short or a fuse could cause a heater circuit issue..
What's the code that's being generated?

 

[EddieC]

I have seen where a short or a fuse could cause a heater circuit issue..
What's the code that's being generated?

P2271

What fuse is involved in that system?

 

[Just Fishing]

P2271

What fuse is involved in that system?

In my wife's old car, there was a short in the wiring that caused the O2 sensor to look like it failed.
that in turn also took out a fuse.
Once I fixed the short, I still didn't have power.

It has been a looong time, but I recall that fuse not being the easiest thing to find.

Happen to have a volt meter that can check ohms? and even better yet one that sends out the beep signal when it shows 0 resistance?
Go through every single fuse, start with the ones that sound correct.
engine bay fuse block to start, most likely there.

If fuses check out,
I would probably start by checking for voltage going to that circuit with the O2 disconnected.

If the issue is just on one side, check the "Good known" side for a reference.
Do an ohms check with the power off to look for a short circuit on the heated sensor side.
Also look over the plug on that "new" o2 carefully.

And if that's the only code for the bank 1 side, then also try flipping the sensors around to see if the code follows the sensor.

If not wiring or a fuse,
Depending on where you bought the sensor, look at it with suspect.


P2271 - searching on that, I see it mentioning an issue with the heater circuit.
And the sensor not switching from rich to lean (or something close to that).

P2271, P2273 O2 Sensor Signal Stuck Rich

The Powertrain Control Module (PCM) detects the Downstream O2 sensor does not transition from a rich to lean condition within a specific time during a DFSO event. Default action this DTC the MIL light illuminate.

www.obd2-code.com