Can't reset CEL

[1996 328ti]

Here's the deal.

I had a local guy replace my subframe bushings.
He went over the car and said he tightened up the 02 sensors and bolts on my headers. IDK why he was messing with it. Guess he was doing me a favor.

I leave the shop and my CEL is ON. I scan the codes with my Peake while at the shop. Two bad precat sensors. He checks it on his scanner. Same thing. He measures the voltages. Both within spec. He tries to clear the codes. Nothing.

I hook up Torque to see if I can measure voltages.
I can see my OBD-II to BT adapter is connecting to my phone but not to the ECU. I try another adapter and my Nexus7. Same thing.

So what is in common is that Torque, shop's scan tool and my Peak are all having problems with the ECU.

My car runs fine. Haven't noticed anything with gas mileage.

Do I need to bring my car to the dealer and have them connect it to their Modic to clear the codes?

So far googling says to replace both sensors.
But the values are normal.
And even if the sensor was bad, I should be able to clear the code even for a short period. The CEL goes off for a second but the faults never go away.

[Mallard]

try a battery reset,
and then see if you can reset the CEL / read the codes.

I would also see if he didnt mix up the two sensors, if he disconnected them whilst messing around down there..

at the very worst, get a proper fixed cable obd tester on there.

[bmwconnect]

You may need to do a adaption reset and if that is the case then you will require at the very least a INPA tool + software or dealer

[1996 328ti]

I don't think he removed either sensors.

My ECU is sharked and NickG did some custom overwriting to the code to eliminate 3 faults from the conversion.

What is the battery test? Disconnect the battery and try again?

[lazoh]

Originally Posted by 1996 328ti

What is the battery test? Disconnect the battery and try again?

Disconnect the battery for 20 minutes, re-connect it and see if that takes care of the problem.

[1996 328ti]

Originally Posted by lazoh

Disconnect the battery for 20 minutes, re-connect it and see if that takes care of the problem.

Disconnected the battery for an hour. Only thing now is it's idling a little rough.

The fact that I can't reset the CEL even for a few minutes and Torque doesn't see the ECU is telling me it's something bad.

Plus my E30 is down until I replace the water pump.

I'm running out of cars.

[lazoh]

Originally Posted by 1996 328ti

Disconnected the battery for an hour. Only thing now is it's idling a little rough.

The fact that I can't reset the CEL even for a few minutes and Torque doesn't see the ECU is telling me it's something bad.

Plus my E30 is down until I replace the water pump.

I'm running out of cars.

If you were closer I would let you use my ti, contact the guy that remapped your ECU and did you check into the O2 sensor wires been crossed?

Sorry Steve and hope that anyone else jumps in here to help you fix this issue.

[1996 328ti]

Originally Posted by lazoh

If you were closer I would let you use my ti, contact the guy that remapped your ECU and did you check into the O2 sensor wires been crossed?

Sorry Steve and hope that anyone else jumps in here to help you fix this issue.

I'll have to ask my guy if he crossed the wires, but don't understand how that would cause a problem.

The guy didn't remap the ECU. He wrote out faults for exhaust flap, fuel pressure and secondary air pump.

I guess I can pull off the fuel rail cover and reverse the wires that way?

[lazoh]

Originally Posted by 1996 328ti

I guess I can pull off the fuel rail cover and reverse the wires that way?

Don't know but if its easy enough to reverse, I say you do it and see if it makes a difference.

[30yrMbr]

Just had an issue with my Ti. The CEL light came on, had the codes read, shows similar error (it was code 1174), and replaced both O2 sensors, and two relays, next to the fuse box. One of them was to control heat for the O2 sensor(?). That worked briefly, then the CEL is back. Had a GT1 scan tool read the codes and search test each of them, bottom line, replaced the fuel filter. No more CEL as yet.

Did not have an issue with unable to reset the CEL, just that it came back on almost immediately. Discovered that I had overlooked to replace the fuel filter for waaaay too long, and that was the cause of the light. May also have been time to replace the O2 sensors (157,000miles) but the CEL did come back on after the replacements went on, and it hasn't since the new filter.

Go figure.

Best of luck with the problem.

[1996 328ti]

The sensors are probably original.
But you'd think I could still clear the codes even for a minute.

Haven't changed the fuel filter in years either.

[Mallard]

when he tightened the o2 sensors, he may have stripped a thread maybe, letting false air in.
Can you see if there is any signs of leakage by the sensors?

[1996 328ti]

Originally Posted by Mallard

when he tightened the o2 sensors, he may have stripped a thread maybe, letting false air in.
Can you see if there is any signs of leakage by the sensors?

That would at least explain why the voltages are good.

[Mallard]

i bet you he knackered the flanch

[1996 328ti]

Originally Posted by Mallard

i bet you he knackered the flanch

Best worse case I will need to retap the hole? Worst case, new headers?