Hello,

I have a 2003 Discovery and a week or so a ago my check engine light came on. There were 3 faults pointing toward the o2 Sensors.

The truck also starting running rough at idle like it was about to stall. So after a bit of reading and investigation I replaced all 4 Oxygen Sensors and reset the faults. The truck is running much better (very good actually) however the check engine light came on again. Upon testing it...The only fault was for the o2 sensor Bank 1 Sensor 1...which is brand new. (The other faults are gone)

What should I look at next? MAF? Any input is appreciated.

Thanks,
Ross

 

You needed a tune up not O2 sensors.
When your plugs and wires wear out to much raw fuel gets dumped downstream, the O2's cant compensate, so the ECU reads that as a O2 failure.
Replace your plugs and wires, reset the light, problem solved.

 

The plugs and wires are pretty new.

I noticed while watching the computer there is no reading at all coming from Bank1 Sensor 1. There are quite a few posts around with people with the same problem after replacing the o2 sensors.

I bought a new sensor thinking the first one may have been defective as this was true for quite a few people...but it didn't help. Now I have put 2 new bosch sensors in and still no reading. And replaced the other 3 sensors too.

Not sure what to do now. Let me know if you have any advise.