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Discussion Starter · #1 · (Edited)
I scanned my BMW (1998, 528i) and get the following:

- Both front wheel sensor error
- Passenger airbag error (dash light for airbag is on too)
- "SLOW! Cat overheat" displayed in the dash

I cleared all codes, but they came back.

And, when breaking, just the moment the wheel completely stops, it make a noise from the front brakes/wheels, both side. Is is possible the ABS is playing nuts because of the sensors and think the wheel is blocking?

I have no BMW service here, only ordinary repair shops, so any hint might help me to solve this issue/forward info to the mechanics...
 

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Check your fuel trim numbers; the engine may be running rich, and that will heat up the cats.

Search this site for sensor troubleshooting; there is a diode inside.
 

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Search this site for sensor troubleshooting; there is a diode inside.
Hi Edjack,
I don't think there is 'physically' a diode; but the sensor "acts" like there's a diode inside (methinks).

Anyway, the OP has a lot more going on than just a sensor ... but to edify the OP, checking all four wheel-speed sensors is as simple as poking a DMM into a few holes in the ABS control module harness connector with the ignition off.

See this thread for the details (there's muuuuuch more than you need ... just skip to the sensor test).

My results, for my four sensors, is shown below by way of example.
 

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Discussion Starter · #5 ·
I just checked the plug connected to the ABS. I have a complete different plug, not the one with 42 pins.
My (white) plug only has a couple of round connectors, so I cannot follow the sensor test via multimeter.
 

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Discussion Starter · #6 ·
"SLOW! CAT. OVERHEAT" is still present.
Read the codes, there was something with O2 sensor cylinder 4-6 low voltage.
The mechanics took it out, cleaned it, checked it, installed it back and no codes anymore, but still the "SLOW..." message in the dash.
We cannot get rid of it.
 
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