I've been battling this issue for a while now and cannot figure it out. I was getting 3 error codes: HOME, REFERENCE, and RPM. all controlled by the trigger harness if im correct and sensitive to noise. I pulled the entire harness, ran new wires with insulated connections and wrap the loom with heat reflective tape to reduce excess heat that might cause wire failure. I made sure to run the wires as far away from the alternator as possible to reduce interference and even made a couple extra grounds to the engine. Car fired up and ran just fine at idle, revved the motor and at about 4k the error light came back on. I managed to get rid of the Home error code but RPM and REFERENCE are still there. i spent alot of time in re doing the harness and cant figure out why the errors are still code. Doesn't seem to affect driving at all but id me more comfortable without having a blinking red lights on the ECU. Any ideas?

 

You didn't mention what year your car is.

If a 2nd gen, try another CAS.

If an FD, then try a new set of VR sensors.

If it happens everytime you rev to 4K regardless, then one of the VR sensors is backwards.

 

forgot to mention is 93 Fd 13b REW.

Problem solved: ended up being the wires, shielding was not properly grounded, interference during rev up. proper grounds are essential.