Speed Sensor CEL

[jchangy510]

I bought a BAR'd 91 318i with OBD1 S52 swap from another member on here. I recently switched out the gauge cluster and noticed the previous owner took out the CEL bulb. I installed my new gauge cluster and drove about 15 miles when my CEL turned on. Had a local shop run the code and was told it was throwing a speed sensor code.

Long story short I traced the wires and everything looks good. I took the sensor off the diff and cleaned it. Anyone know what else I can check? Could it be the sensor is bad? Speedo/ RPM and all gauges work.

[ba114]

could have wired the speed sensor to the wrong pins in the x20-c101 plug

[NotJesus]

Theres a few posts about it right here- without the speed sensor, vanos does not engage- the ecu essentially thinks youre sitting at a stop sign revving your engine. In my 87 325, I had to run a wire directly from the c101/x20 to the back of the cluster. Do a search, there are a few threads about it, and its worth a few hp. You should be hitting a soft rev limit at around 5500-6000