Strange codes?

Had my codes done today came up as front bank ,rear bank o2 sensor and my car doesn't have any anyone struck this before?
And no they haven't been removed but I did have the cat removed some years ago.
My car is 98 523i touring originally out of Singapore BMW approved imported to my country @ 38,000 miles.

The car won't run well w/o pre-cat O2 sensors, so you must mean post-cat sensors. If they are in place, the DME will report a cat poerformance problem, since the cat is gone, and not doing its job. If not in place, the DME will set a code that they are missing.

What exactly were the codes?

My fault on the codes,I didn't get the print out from the machine and my man can't remember,I have never had a code come up since I removed the cat,I don't believe I have any O2 sensors after where the cat as I was there when the cat was removed.
My car has 2 welded steel exhaust manifolds and there are no mounting sockets for the sensors anywhere.
Did the inline six ever have 4 sensors?my research tells me only 2?,well for my european model anyway.
With the exception of the cat removal the system is BMW end to end,thanks Ed.

My european 1996 528 does not have post cat o2 sensors as well but have no codes.

Originally Posted by mjalloul11

My european 1996 528 does not have post cat o2 sensors as well but have no codes.

Thanks ,do you have o2 sensors @ the engine then (as in the exhaust manifolds)?

Originally Posted by edjack

The car won't run well w/o pre-cat O2 sensors, so you must mean post-cat sensors. If they are in place, the DME will report a cat poerformance problem, since the cat is gone, and not doing its job. If not in place, the DME will set a code that they are missing.

What exactly were the codes?

Have checked the car and crawled underneath,the cat has been removed as already mentioned,there is a welded in replacement pipe as I mentioned also,went all the way thru the system from end to end any there is no o2 sensor anywhere,

The US spec cars use the pre-cat sensors to adjust the fuel mixture. If your doesn't have o2 sensors, then you must have a different fuel injection system.

I never thought of that. So, the system must run open-loop all the time, using fuel maps that only correspond to to engine temperature and load, just like The Olden Days, before lambda fuel control.

The DME does not look for O2 sensor inputs.

....Or he just missed the oxygen sensors.

Originally Posted by edjack

I never thought of that. So, the system must run open-loop all the time, using fuel maps that only correspond to to engine temperature and load, just like The Olden Days, before lambda fuel control.

The DME does not look for O2 sensor inputs.

Ed you are correct ,a system doesn't need o2 sensors to work,yes the (good IMO) olden days they were less complicated ,have worked on mid model mk2 VW Golfs and my information tells me the UK build cars had no 02 sensor yet many ROW cars did ,for example all Japanese spec cars had them regardless of fuel injection systems.

Steve 530 ,thanks for your input as mentioned the system is all original besides the cat delete pipe,when the cat delete pipe was fitted I carried out a full inspection under the car and there were no sensors infact there no cat overtemp prode as I have seen on parts diagrams for this model.
The PO was a technical manager for the biggest dealership in my country and my car was used extensively for technician training I tend to be sure it is original in that aspect.

Did you determine what caused the codes?

No ,I can only suspect the diagnostic plug has the pins in situ still although the sensors are not present.
Have worked on euro cars for a long time and find a large variation in specs right across the range.

Hmmm. Codes for phantom sensors.

In the US, the OBDII system is required to set the CEL when a component fails that would cause increased emissions. Does you car have a CEL?

I do have two o2 sensors on the exhaust mainfold as well the cat converter but there are NO sensors after that. and yes they do throw a CEL when they are not working.

Mines OBD1,sorry whats CEL short for?

Check Engine Light

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Originally Posted by Steve530

Hmmm. Codes for phantom sensors.

In the US, the OBDII system is required to set the CEL when a component fails that would cause increased emissions. Does you car have a CEL?

I had the test done as I had a misfire (which I haven't fixed ) the codes that I mentioned @ the start of this thread came up and I was curious as I knew then I had never seen the sensors.
The service lights were reset as I had done oil/filter change.
I have been too busy to fix the misfire which I believe is a coil pack,have a spare waiting to fit.
Will post photo of exhaust manifolds I anyone is interested.

Merry Xmas.

Ithink all e39 have OBD2 but i cannot be sure.

If car originally had cats, then it likely had pre-cat O2 sensors. Pre-cat O2 sensors are essential for cats to work. Perhaps they were removed, perhaps you can't find them, perhaps the misfire codes, which will disable fuel injector(s) causing lean exhaust conditions are causing issues for the O2 sensors. Do you have a check engine light? Does it come on in key position 2? Perhaps light was removed and codes have been present since cats & O2 sensors were removed.
Post the last 7 digits of VIN and we can tell you what you should have.

Originally Posted by E39 touring

Have checked the car and crawled underneath,the cat has been removed as already mentioned,there is a welded in replacement pipe as I mentioned also,went all the way thru the system from end to end any there is no o2 sensor anywhere,

Originally Posted by mjalloul11

Ithink all e39 have OBD2 but i cannot be sure.

Have round OBD1 test plug in my car and it is the older 5 series ones,my check service resetting tool only works for OBD1 also.


pshovest thanks for your input,the car only had 1 small cat @ the junction of the twin downpipes,it was removed because the cells collapsed inside and were rattling and @ times blocking of the exhaust.
Not sure when you say the injectors shut down on a misfire,have had wet plugs in the past with a previous coil failure
Vin is BY87483,thank you for your help and forgot to mention I have no check lights on

Originally Posted by E39 touring

I had the test done as I had a misfire (which I haven't fixed ) the codes that I mentioned @ the start of this thread came up and I was curious as I knew then I had never seen the sensors.
The service lights were reset as I had done oil/filter change.
I have been too busy to fix the misfire which I believe is a coil pack,have a spare waiting to fit.
Will post photo of exhaust manifolds I anyone is interested.

Merry Xmas.

Yea, that's interesting. You'd think they would have handled that better in the software.

BTW, I had misfire codes last week after inadvertently disconnecting a hose on the CCV. So a vacuum leak can cause a misfire. And vacuum leaks are common. Of course, a bad coil can, too.

pshovest is writing about misfire with fuel shutoff. I think the DME shuts off the fuel in cases of sonsistent misfire to prevent unburned fuel from overloading the catalyst.

US spec BMW's have a CEL, Check Engine Light, that turns on when there are codes stored. Did you have a light on dash when you found misfire codes? Need to find out if you have a similar light or if you are suppose to have a similar light. On US cars, running without pre-cat sensors will turn on CEL.

Looks like there was an option for Catalyst delete on your car. See upper right corner of attachments.
Pre-cat O2 sensors may be on backside of exhaust manifold making them difficult to see.

Car is now running poorly,have spent a fortune on plugs and coil pack,have been looking for air leaks but have have no luck.
CVV changed last year along with hoses and pipes,fuel economy is bad with wet spark plugs and under load misfire that isn't like a coilpack failure (been there).
I'am looking @ replacing fpr and cam cover gasket as the last resort.
My patience is running out as I meant to be on holiday

Wet plugs you say?
Have you checked your cold start circuit?

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If you're searching for a vacuum leak, you might want to check out this post where Blubee put together a smoke machine.