1998 528i BMW

[Young 23]

I have an e39 BMW with the m52 engine. I did a head gasket on my car and it drives great so far after nearing 1,000 miles. Codes P1189 and P0154 came up today. The first says “Fuel control (bank 2 sensor 1)” while the last code reads “O2 circuit no activity detected (bank 2 sensor 1).” I replaced both precat sensors last year before my head gasket blew. Any ideas what this means? As in I replaced both sensors so why would the sensor not detect activity? Does it need to be changed again? The check engine light is on but when I drive nothing feels out of place. I do get an occasional rough idle on start ups (I did clean the ICV), but one day it’s there and then it’s not. The replacement sensors were NTK and installed at the same time and the codes were read by autozone.

[shogun]

moved to E39 forum

[m735is]

Do you have a program to read the sensors while the car is running? I use Dash Command with a wifi adapter. That way you can check the O2 sensor in action and see if it's really dead.
You can try cleaning the sensor- clean out the slits and spray some carb cleaner in it and put it back. It may come back to life. Maybe it got contaminated since you replaced it before the head gasket job??

[mattmar1]

check the condition of the wiring along the valve cover for the precat o2's, its been known to break. and as stated above, read the activity of the sensors using a reader capable of giving you the live data from the engine. non bosch o2 sensors seem to be unreliable on these cars.

[geargrinder]

check the condition of the wiring along the valve cover for the precat o2's, its been known to break. and as stated above, read the activity of the sensors using a reader capable of giving you the live data from the engine. non bosch o2 sensors seem to be unreliable on these cars.

^^^ 100% concurrence.

Also: Thanks for mentioning the HG repair - lots of times guys forget to mention something that was done in and around the problem. If your headgasket problem puked lots of stuff down the exhaust there's a chance that it contaminated the sensor (or if your mechanic used silicone on something where he wasn't supposed to...) and kilt it. And if you said "yeah I know the HG failure was on bank 2 cylinders..." that'd add some support for that theory.

I would disagree with the 'clean the O2 sensor' suggestion, AFAIK you really should avoid touching those things as much as possible and trying to clean 'em either is just pure BAD, or, at best won't do anything if the sensitive material the sensor is made of has been contaminated and not is not 'wash off' type contamination but is 'toss it' contamination.

[Young 23]

Do you have a program to read the sensors while the car is running? I use Dash Command with a wifi adapter. That way you can check the O2 sensor in action and see if it's really dead.
You can try cleaning the sensor- clean out the slits and spray some carb cleaner in it and put it back. It may come back to life. Maybe it got contaminated since you replaced it before the head gasket job??

That’s a very good point. I was not able to check the sensors via a scanner as I don’t have one, but the contaminating of the sensor with the burning if the coolant is plausible. Nevertheless, I did end up replacing it with an NTK sensor and that solved my issue since I passed emissions and the light turned off and has stayed off ever since. But I will look into possibly using that WiFi dash command. Seems useful. But thanks again for the info!

[Young 23]

check the condition of the wiring along the valve cover for the precat o2's, its been known to break. and as stated above, read the activity of the sensors using a reader capable of giving you the live data from the engine. non bosch o2 sensors seem to be unreliable on these cars.

I did check the wiring and it was entirely intact. As for a scanner to check the live data of the engine I have not been able to due to not having a scanner. However, I did end up replacing the sensor and I ended up passing emissions and the light turned off and stayed off. So although a scanner is needed, at least the issue has been resolved. And maybe? I just put in an NTK sensor bc that’s what I took out. Whether they are currently of the same quality as before is beyond me, but maybe in the future I will purchase Bosch sensors,l. They are compatible with the m52 engine correct? Anyways thanks for your feedback! Much appreciated!

[Young 23]

^^^ 100% concurrence.

Also: Thanks for mentioning the HG repair - lots of times guys forget to mention something that was done in and around the problem. If your headgasket problem puked lots of stuff down the exhaust there's a chance that it contaminated the sensor (or if your mechanic used silicone on something where he wasn't supposed to...) and kilt it. And if you said "yeah I know the HG failure was on bank 2 cylinders..." that'd add some support for that theory.

I would disagree with the 'clean the O2 sensor' suggestion, AFAIK you really should avoid touching those things as much as possible and trying to clean 'em either is just pure BAD, or, at best won't do anything if the sensitive material the sensor is made of has been contaminated and not is not 'wash off' type contamination but is 'toss it' contamination.

No problem my guy! I just figured I should be thorough as I’m not exempt from making mistakes and I want y’all to know everything so hopefully you guys can steer me in the right direction. And that’s a great point! I hadn’t thought of that but now that you two mention it it makes much more sense. And yea, cylinder 4 had a good pool of coolant in it and the exhaust prior to disassembly blowed white, sweet smelling smoke as it burned the coolant. Regardless I ended up changing the sensor with an NTK sensor. I passed emissions and the light turned off and hasn’t come back on so that’s a plus for me. I do the majority of work on my car so I didn’t use any silicone or anything that may mess with the sensor, but yea I just replaced it, I didn't try to clean it as it wasn’t too expensive. I did do the job on my car and fortunately everything worked out well. Thanks for all the advice!!!