02/lambda code 21 ..help

[[email protected]]

getting an error code 21, o2 sensor. mpg verifies this.
the sensor (denso)has seen 8000mls from new.
could a sensor die in such a short time ??
Also, doing the bgb test,would it show as a code 21 if it was a wiring fault ?
basically ..I need ANY help with best way to proceed ect
do i have to do a continuity test on the 4 wires first and ecu ( no idea how to test ecu) or can a test be done using wires nearer sensor??

[SonicSW20]

It could if EGT's are excessively high, or it is burning oil, or overfuelling excessively.

21 is o2 sensor heater circuit isnt it?

[[email protected]]

code 21 is not specific, just o2 sensor !

had no issues with burning oil, not aware of any issues with overfueling.
if sensor is dead then i will investigate the cause ..
just dont know the best coarse of action ?

[Juliuswws]

Have you got a multimeter?
I would check all wires first. I guess all 4 goes to ECU.
Sensor could also be checked with multimeter. Both the heater coil and the sensor.