[00Mustang]

My car was throwing a trouble code P1413, SAI Circuit low voltage, i replaced the smog pump, check engine light went away for a while, but now its back, i checked to see if the smog pump would suck in fresh air from a cold start and it did so i know the smog pump is working, now, i have heard that the rear O2 sensors could also make your car throw a P1413 trouble code, is this true?

[tripleblack]

It probably does involve the pump, just not the pump itself.

Things it could be:

1. Wiring fault, B+ Circuit, AIR circuit (could be short to ground), etc.

2. PCM damaged

3. Bad solid state relay

If I had to guess, I'd go with the relay. There's a test routine for this, but I don't know it off the top of my head.