2G Help! Multiple engine codes P0135, P0141, P0120, P0105 after 4G64 swap.

[NVdsm]

Backstory on the car is it’s a 96 GST I got as a bare shell for cheap. It’s a budget project for fun. I used what I had or could get for cheap. I swapped in a 98 Spyder 4g64 into it. I kept it non turbo so I got a 98/99 wire harness and ECU for it.

Car starts and runs good. However I’m getting 4 fault codes that start to pend within minutes of resetting it. It’s for P0135, P0141, P0120, and P0105.

So both O2 sensors, TPS and mass airflow sensor. I’ve swapped mass airflow sensor out with a known good one and the upstream O2 sensor is brand new. I have a scan gauge and it shows my O2 sensor reading pegged at 1.275V never changes. And if I unplug it, it still reads 1.275V.

Could this maybe be the ECU? Don’t all these sensors get their signal ground from the ECU pin 92?

 

[Bigmike4g63t]

When you changed out the plug did you change the wire as well?

 

[NVdsm]

When you changed out the plug did you change the wire as well?

The o2 sensor? I bought one from oreilly specifically for the spyder gs its plug and play with sensor and wire/plug already ready.