have code 20 (voltage overload) and a code 13 (atmospheric pressure)
does anyone know what might cause these car seems fine but check engine lite is on. any help would be great
Thanks

 

I don't see a code 20 for an EF. relevant Helm's manual pages attached

 

Of the question is You have a code 20. Code 20 is an ELD (Electronic Load Detector). This ELD is located in the under the hood Fuse Box on all Civic, CRX 1988-1991. This is your source of your problem. Theres a catch. The ELD was typically found on the civic/CRX models that came with the 1.6L multiport fuel injection engine.

So to break it down, lets say your car came with an original Dual Point injection 1.5 Litre engine and you swapped it out for a 1.6 single cam, DOHC ZC, or you could have just swapped out the Duel point injection manifold and installed a muliport injection manifold. If you did any of these things, You have changed out your original 1.5 ECU for the 1.6 ECU. If this is your scenerio, Your ECU is lookling for something its never going to find. That being the ELD. People do this swap all the time and that code flashes for days without giving any problems. You can change the underhood fuse box if this is the problem. There might be some extra wiring you might have to do but its been a while since i did a swap in one of those so do a bit of research on that extra wiring bid.

If you have an original Si and have not done any of the mentioned above, then look at replacing that underhood fuse box. Code 13 that sensor is found inside your car above the passenger side kick panel.