That's a handy bit of info, I was terrified of touching the plugs as I couldn't find the torque setting anywhere. Thanks for that!
The front sensor only fluctuates when on the motorway with the revs over 4000rpm but still stays over 700mv.
The thing that's confusing me is i've read that a high voltage from the sensor means a rich mixture, and the front sensor is used to correct air/fuel ratio.
If this is true, and the rear sensor is ok my car must be running lean as the average reading from the rear sensor is about 35mv. But i'm using a full tank of fuel every 200miles, which I thought was because it was running rich.
If I disconnect the front sensord, the ecu still reports a reading for it (fluctuating between 400 and 500mv at idle) and the engine runs much smoother, but the rear sensor reading still drops way below 100mv once the engine is warmed up.
Also, I get an error code for the heater circuit on the front sensor connected or not, but have heard this can also be caused by the rear sensor being faulty. Is this true? :?
It looks to me though, as if the ecu uses the reading from the rear sensor to work out air/fuel ratio and when it drops voltage as it warms up the ecu is putting more fuel in to correct the lean reading, but as the rear sensor doesn't react to the change it keeps putting more fuel in which would cause the working front sensor to show the highest reading possible as the exhaust gas is very rich.
Or am I looking at this completely wrong? notsure.gif