Engine starts and runs but ECU throws immediate code 21.

Here is what I have done..

3 different ECUs give same code. currently have non chipped stock p28

I have triple checked wiring from solenoid to A4 on ECU harness. ---Good
I jumped solenoid to 12v and solenoid clicks. Added temp ground wire to solenoid housing...no change.

The code shows immediately even after ECU reset. The CEl light does not dropout at start. As soon as key goes to accessory the cel comes on and stays on. Even after ECU reset (which seems odd).

Using EX engine harness and added 2 pins to shock tower harness and 2 pins to ECU harness for solenoid and pressure switch. Wires are soldered and check good for continuity..

Any ideas?

 

thats limp mode, turn the key on and the CEL never goes out you have an open ground probably.

 

Ok, thanks for the info..I can check the grounds at the thermostat housing....Are there any other points to check that would typically cause this? It must be something in the engine harness since the car was fine before the swap with the d15 harness.

 

isnt there one from the valve cover to the chassie? i know my old motor had it and so does my b series now.

 

Yeah, I have that one still connected. I can check it for corrosion...I think it is ok though.