Thanks for your reply, It is the sensor before the cat bank 1 s2 that is causing the problems. I have changed the engine loom over to rule out wiring etc. Really at a loss.

Hello, I hope you can help me as i am at my witts end with this fault. Basically my car has three lamba sensors two at the precat and one at the cat It is an alfa 147 1.6 tspark. Bank1 s1 and bank 2 s1 are flucuating from rich to lean normally, However bank 1 s2 is sitting at a steady 0.45 volts. I ...