Hi Guy's,
I have a Celica GT Jap Import does anybody know which wire's are which on a 4 wire O2 sensor, I have 2 black, 1 white,1 blue.
I need to replace my O2 sensor & I can get one but I have to wire it up to my existing plug socket.
The one I have been offered has the following wires,

1 signal (black)
1 12v supply (white)
2 earth (1 grey and 1 white)

i am not so sure about the 2 earths? what for?

One earth is for the heater and one for the sensor.

Ok....in the original sensor the white wire is the signal wire, 2 blacks are 2 earth and the blue one is the heater. Hope this helps!!! >> >> >> >>

Thanks Edo for your information much appreciated.