E34 without O2 Sensor have 1221 Error Code

[Dave M]

1991 CAN M50 with Cat from factory. Cat was removed by the previous owner who had a (very thick walled) straight pipe welded in with a thread for an O2. Car runs as it should.

Dave

[whiskychaser]

1991 CAN M50 with Cat from factory. Cat was removed by the previous owner who had a (very thick walled) straight pipe welded in with a thread for an O2. Car runs as it should.

Dave

Now that I can understand. But as OP states he has an OE non-cat front box, there is nowhere to put the O2 sensor. I may not be the only assuming OP was indicating he doesnt have an O2 sensor either. Perhaps he can confirm?

[Tiger]

REDLEF, either install a new aftermarket cat and O2 sensor

or

cut a hole in the straight pipe, weld in a nut for the O2 sensor thread and put O2 sensor in.

[Dave M]

REDLEF, either install a new aftermarket cat and O2 sensor

or

cut a hole in the straight pipe, weld in a nut for the O2 sensor thread and put O2 sensor in.

This is why I posted my photo. Also, if I had to guess, I would say the vehicle came with a cat.

Dave

[redled]

This is the exact parts installed in my car. No modification or repair yet. Original parts.
Where can I put a hole for the sensor and do you think it will work w/out cat?

[Tiger]

Hmmm... since we know the car is US import... the ECU is probably US version for cat... do you think you can source a ECU of similar engine in your country? This might be easier.

Putting an O2 sensor would be just at the bend where the pipe comes down from engine and straightens out to the muffler.

[whiskychaser]

This is the exact parts installed in my car. No modification or repair yet. Original parts.
Where can I put a hole for the sensor and do you think it will work w/out cat?

I think Tiger already answered that and Dave M gave you a work around. I would go with Tiger's option a. as:

1. You are going to blow a hole in a 20+ year old exhaust pipe if you try to weld it
2. If you fit the O2 sensor to a straight pipe before the silencer box it is only going to read off 3 cylinders
3. IMHO that is what it supposed to have to make the car run properly :-)

[redled]

If I can't find CEU here, there is no option I have to install sensor. Where is the electrical connection for O2 sensor located and how to know if it is for that sensor.

[genphreak]

Talk to millerperformance.com, someone on the WAR chip forum might be able to share a suitable bin file with you.

To add an O2 sensor you would have to add the factory cat and engine pipe assembly (easy to source in the US- all M50 powered 525is had them) and they come with the sensor, wire and plug. Ask for the wire support/metal encasement, plastic bolts and so on too.

Does your car have the female side of the sensor plug on the LHS of the engine? It's about 40mm in diameter, goes through a black metal bracket mounted down under the intake.

[redled]

Yes there is. Its hard to find factory cat and engine pipe assembly here in the Phils.
I might do what Dave did in his car.