Oxygen sensor for GU

Hey Robin

Thanks for the reply....so I will be better off letting them do it and they said they will put it back onto the dyno for free, so might be worth it in the end getting them to do it

That's exactly the way to do it - as Robin correctly points out, the O2 sensor has a large input into the fuel mixture - if it's completely shot, the car will run in open loop the whole time, meaning it's super rich and using lots of fuel. If it's halfway shot, the car could be running too lean or too rich for extended periods.

In fact, the purpose/effect of the O2 sensor is to change the mixture between too rich and too lean many times a second and hence get an averave good mixture (as defined in your ECU).

cool

the bloke said it's still working but it's "slow" and on the way out. So hopefully putting in a new one will make a huge difference to my fuel bill