O2 Sensor Issues

MikeYQM · 08-29-2021, 02:33 PM

I am having recurrent issues with upstream O2 sensors.

For the last 10,000 km or so I have been getting two pretty distinct sets of issues with my O2 sensors.

1. I think I know the issue on this but I've gotten Code P0135 - which is the B1S1 O2 Heater fault. I've swapped the plugs and replaced and it keeps randomly popping up. Seems to occur more in the rain and I *think* I've narrowed it down to a wiring/harness issue. It throws a CEL and code and seems exclusive to B1.

2. I'm also getting random transient errors for "Open Loop Due to System Failure". This does not appear to be linked to environmental conditions, it does not throw a code or appear to affect driveability in any way. On my OBD reader I'm able to confirm that Lambdas are stable between banks, O2 current is stable between banks, fuels trims, Cat Temps, O2 heater temp and O2 Heater resistance all appear normal. It simply resets itself when I restart the car and doesn't occur for another few hundred KM's.

Does anyone have experience with the "open loop due to system failure" being transient between banks and showing no real symptoms?

I've been on 3 sets of O2 sensors with minimal change in frequency. I've been on 2 tunes with no change. I've gone from test pipes to a custom X-Pipe with no change and I've adjusted/leak checked the exhaust countless times.

Redd · 08-29-2021, 07:18 PM

I don't have experience with this but I assume if the DME cannot reach the O2 sensors for a while it would go into open loop and log the error? Sounds like you have a wiring issue.

MikeYQM · 09-25-2021, 03:21 PM

Well, I swapped sides on the B1 <-> B2 upstream O2 sensors and (knock on wood) haven't had a P0135 heater code since. Noticed there was a pinched cable on one harness.

After switching sides, the Open Loop Due to System Failure issue followed from B1 to B2. So I replaced that O2 sensor with new. The wires must have been damaged from the pinch because I started getting P112C codes and the O2 Current wasn't reading very well… slow update frequency compared to B1 and Lambda didn't change similar to B1 in rate and magnitude.

I am still getting transient "Open Loop Due to System Failure" on my logging app. It randomly pops up with no symposiums. About every 50-100km or so. No codes, no symptoms. It just shows "Open Loop…" until I restart the car.

Any ideas?

munstro · 09-25-2021, 06:50 PM

I’m not a mechanic but I’ve been through this before. Try updating to current software. If this doesn’t work the next option is a new DME to see if that works. Then it would be the wiring harness, and then you may need new cats. This was the process for me. It’s extreme measures but I wasn’t going to stop until I got the issue resolved. Very time consuming and thankfully done under warranty. Lots of people will tell you to check the donuts on the exhaust. My mechanics didn’t go there because they knew that was not the issue and they weren’t going to do work for me that they knew wouldn’t fix the problem. My car only had less than 40k on it when this issue arrived for me. If you look way back and search the forums you’ll see another owner with a low mileage car that went through the exact same process as me to fix the car. I also had no symptoms ither than the light.

08-29-2021, 02:33 PM	#1
MikeYQM Private First Class 80 Rep 143 Posts Drives: 2013 BMW M3 ZCP Join Date: Nov 2019 Location: Moncton NB Canada iTrader: (0)	O2 Sensor Issues I am having recurrent issues with upstream O2 sensors. For the last 10,000 km or so I have been getting two pretty distinct sets of issues with my O2 sensors. 1. I think I know the issue on this but I've gotten Code P0135 - which is the B1S1 O2 Heater fault. I've swapped the plugs and replaced and it keeps randomly popping up. Seems to occur more in the rain and I think I've narrowed it down to a wiring/harness issue. It throws a CEL and code and seems exclusive to B1. 2. I'm also getting random transient errors for "Open Loop Due to System Failure". This does not appear to be linked to environmental conditions, it does not throw a code or appear to affect driveability in any way. On my OBD reader I'm able to confirm that Lambdas are stable between banks, O2 current is stable between banks, fuels trims, Cat Temps, O2 heater temp and O2 Heater resistance all appear normal. It simply resets itself when I restart the car and doesn't occur for another few hundred KM's. Does anyone have experience with the "open loop due to system failure" being transient between banks and showing no real symptoms? I've been on 3 sets of O2 sensors with minimal change in frequency. I've been on 2 tunes with no change. I've gone from test pipes to a custom X-Pipe with no change and I've adjusted/leak checked the exhaust countless times. __________________ 2013 Fire Orange II E92 M3 ZCP Bimmerworld (Quad) Resonated X-Pipe, AFe Stage 2 CF Intake, Carbon Project CF Plenum, Epic Motorsports Race Tune, Rogue Engineering Power Pulleys, Continental Extreme Contact Sport
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08-29-2021, 07:18 PM	#2
Redd Brigadier General 3900 Rep 4,165 Posts Drives: 2010 BMW E92 M3 Dakar Edition Join Date: Jul 2015 Location: Malaysia iTrader: (0)	I don't have experience with this but I assume if the DME cannot reach the O2 sensors for a while it would go into open loop and log the error? Sounds like you have a wiring issue.
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09-25-2021, 03:21 PM	#3
MikeYQM Private First Class 80 Rep 143 Posts Drives: 2013 BMW M3 ZCP Join Date: Nov 2019 Location: Moncton NB Canada iTrader: (0)	Well, I swapped sides on the B1 <-> B2 upstream O2 sensors and (knock on wood) haven't had a P0135 heater code since. Noticed there was a pinched cable on one harness. After switching sides, the Open Loop Due to System Failure issue followed from B1 to B2. So I replaced that O2 sensor with new. The wires must have been damaged from the pinch because I started getting P112C codes and the O2 Current wasn't reading very well… slow update frequency compared to B1 and Lambda didn't change similar to B1 in rate and magnitude. I am still getting transient "Open Loop Due to System Failure" on my logging app. It randomly pops up with no symposiums. About every 50-100km or so. No codes, no symptoms. It just shows "Open Loop…" until I restart the car. Any ideas? __________________ 2013 Fire Orange II E92 M3 ZCP Bimmerworld (Quad) Resonated X-Pipe, AFe Stage 2 CF Intake, Carbon Project CF Plenum, Epic Motorsports Race Tune, Rogue Engineering Power Pulleys, Continental Extreme Contact Sport
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09-25-2021, 06:50 PM	#4
munstro New Member 10 Rep 29 Posts Drives: 2013 e92 M3 frozen white Join Date: Sep 2018 Location: Arizona iTrader: (0)	I’m not a mechanic but I’ve been through this before. Try updating to current software. If this doesn’t work the next option is a new DME to see if that works. Then it would be the wiring harness, and then you may need new cats. This was the process for me. It’s extreme measures but I wasn’t going to stop until I got the issue resolved. Very time consuming and thankfully done under warranty. Lots of people will tell you to check the donuts on the exhaust. My mechanics didn’t go there because they knew that was not the issue and they weren’t going to do work for me that they knew wouldn’t fix the problem. My car only had less than 40k on it when this issue arrived for me. If you look way back and search the forums you’ll see another owner with a low mileage car that went through the exact same process as me to fix the car. I also had no symptoms ither than the light.
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