Heated O2 Sensor Readings?

[Just Fishing]

More on that code from the FSM,
P2271
• DTCs P0036, P0037, P0038, P0137, P0138, P0140, P0141, P0443, P0458, P0459, P2232 are not set.

• The Ignition 1 Signal parameter is between 10-18 volts.

• The Engine Speed parameter is between 500-5,000 RPM.

• The MAF Sensor parameter is between 3-50 g/s.

• The Vehicle Speed parameter is between 24-132 km/h (15-82 mph).

• The Fuel Level Sensor parameter is more than 10 percent.

• The Loop Status parameter is closed.

• The engine run time is equal to or more than 5 minutes.

THEN

• DFCO is active.

• The APP is stable.

• The TCC is locked.

• DTCs P013A, P013C, P013E, P014A, P2270, and P2272 have run and passed.

• DTC P2271 runs once per drive cycle when the above conditions are met.


P2271
The ECM does not detect an HO2S voltage less than 150 mV before accumulated mass air flow exceeds 550 grams

 

[Just Fishing]

Circuit/system testing.

Ignition OFF, disconnect the scan tool and wait 60 seconds to ensure all modules are powered down.
Ignition OFF, disconnect the harness connector at the appropriate HO2S.
Ignition OFF, measure for less than 5 ohms between the appropriate HO2S low signal circuit terminal A and ground.
⇒ If more than the specified range, test the appropriate HO2S low signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

Ignition ON, verify the appropriate scan tool HO2S parameter is approximately 450 mV.
⇒ If more than the specified value, test the appropriate HO2S high signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

⇒ If less than the specified value, test the appropriate HO2S high signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

Ignition ON, install a 3A fused jumper wire at the HO2S high signal circuit terminal B. Toggle the jumper wire between the HO2S low signal circuit terminal A and battery voltage. Verify the appropriate scan tool HO2S parameter toggles between 0 mV and approximately 1,000 mV.
⇒ If the appropriate scan tool HO2S parameter does not toggle correctly, test the HO2S high signal circuit for an open/high resistance. If the circuits test normal, replace the ECM.

If all circuits test normal, replace the appropriate HO2S.

 

[Just Fishing]

Basic wiring, and fuse diagram (for my 09)
I don't know what year/model you have, but I'm assuming they are pretty much the same thing.


Also make sure that sensor hasn't been plugged, contaminated, blocked etc.

 

[EddieC]

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

Just a thought on the several heater circuit concern comments, would the system send a code right away on cold start if the heater circuit was not working? Lately the error codes don't occur until after many mile(30-40) so it seems like the heater should be out of play by then but I'm just spit balling.

To answer your question, the new sensor came from Rock A and came in an official looking GM box. As a second comparison backup got another from Amazon and it came in the same appearance GM box. I checked the resistance of the pair of white wires on both the original (assumed failed) sensor and the Amazon GM sensor and they were the same at 6.7 ohms. I have yet to crawl back under to check the Rock A GM sensor still in there, but I'm guessing it's going to be the same. I will add that the original sensor did have some dusty carbon deposits around the based of the sensor if that means anything.

I have to get a test light and get in the fuse box to continue.

Yesterday I cleaned the MAF sensor and so far, after a reset and the cleaning, 30 miles without an error. Fingers crossed again.

Thanks for the technical link.

I sure miss the hot rod motors of the 60's!

 

[EddieC]

Another day without a code so perhaps cleaning the MAF sensor was the key.
I never realized it could be a maintenance item but then again we haven't kept a daily driver vehicle for 15 years before.

 

[Just Fishing]

More on that code from the FSM,
P2271
• DTCs P0036, P0037, P0038, P0137, P0138, P0140, P0141, P0443, P0458, P0459, P2232 are not set.

• The Ignition 1 Signal parameter is between 10-18 volts.

• The Engine Speed parameter is between 500-5,000 RPM.

• The MAF Sensor parameter is between 3-50 g/s.

• The Vehicle Speed parameter is between 24-132 km/h (15-82 mph).

• The Fuel Level Sensor parameter is more than 10 percent.

• The Loop Status parameter is closed.

• The engine run time is equal to or more than 5 minutes.

THEN

• DFCO is active.

• The APP is stable.

• The TCC is locked.

• DTCs P013A, P013C, P013E, P014A, P2270, and P2272 have run and passed.

• DTC P2271 runs once per drive cycle when the above conditions are met.


P2271
The ECM does not detect an HO2S voltage less than 150 mV before accumulated mass air flow exceeds 550 grams

I didn't clarify it in this posting, I believe this is what has to happen in order to trigger that code.
Do you have any others that pop up, or just that one?

 

[EddieC]

It was wishful thinking that cleaning the MAF sensor cured it. It did for another 40 miles, then not.
It had been only one error code but previously was a stuck lean error but lately stuck rich.

Checking the new current codes today was the first time multiple codes; 1st , P2270, stuck lean on Bank 1 Position 2 followed by P2271, stuck on rich on Bank 1 Position 2 (same O2 sensor as always), followed by U0073, control module communication bus off.

Fuses checked out ok so crawling under there with an ohmeter.

 

[EddieC]

Hoping the simplest solution is the right one. Ohm meter showed odd reading on one of the heater (feed) wires.

After prying the connector off the top of the frame to get a better look, two wires (one heater) showed cracks in the insulation and it looks like the copper heater wires were broken and held together by the insulation which was very hard and inflexible. Maybe the intermittent loss of contact was causing the issue.

There is just a short piece of each of the two iffy wires outside the connector so I'm testing my seldom used soldering ability. I see that replacement connectors are available but that will be a fall back plan. I'm not fond with the fact that the wires on the replacements are not color coded and that can cause confusion in the future.

Hopefully this is the last "thank you" for all the input.

 

[Fless]

Hoping the simplest solution is the right one. Ohm meter showed odd reading on one of the heater (feed) wires.

After prying the connector off the top of the frame to get a better look, two wires (one heater) showed cracks in the insulation and it looks like the copper heater wires were broken and held together by the insulation which was very hard and inflexible. Maybe the intermittent loss of contact was causing the issue.

There is just a short piece of each of the two iffy wires outside the connector so I'm testing my seldom used soldering ability. I see that replacement connectors are available but that will be a fall back plan. I'm not fond with the fact that the wires on the replacements are not color coded and that can cause confusion in the future.

Hopefully this is the last "thank you" for all the input.

I agree with the frustration re replacement pigtail lead colors lacking. Before you solder you can slip a short piece of the right color shrink tube over the new wire and shrink it close to the new connector, to retain some semblance of the wire color.

 

[EddieC]

I agree with the frustration re replacement pigtail lead colors lacking. Before you solder you can slip a short piece of the right color shrink tube over the new wire and shrink it close to the new connector, to retain some semblance of the wire color.

Good idea. I intended on using liquid electrical tape to coat the solder because they are tight spots close to the connector. Then I can wrap the whole bunch with tape. The old tape was hard as a rock and needed a heat gun to soften it up to peal it back. PIA working on the ground.