Recently I got a Code for OMP Stepping Motor and OMP position sensor (20 and 27 IIRC) I was wondering what tests I could do to rule out that the OMP is bad because the light comes on intermittently. I researched and couldn't find any tests, but someone stated that OMP Failure for S5's is common and that even if I replaced the OMP, that there's a good chance the OMP circuit on the ECU is damaged. Is this true? If it is am I better off going to Rtek? The car is a 1990 N/A. Thanks.

 

First STOP DRIVING THE CAR! Don't assume the ECU is already burned.

Then this is the thread to test the MOP. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/s5-mop-ecu-failure-diagnosis-710938/

Test your old MOP to practice. Then you should also test any MOP that you buy used to verify that it is fully functioning.

Once you get a fully functioning MOP, you will find out if the ECU is good. If it is not, then you can decide if you want to RTEK it or find a replacement MOP.

Good Luck!

-Jack