I have a 2000 Express 3500, 5.7 ltr V-8
It had been setting codes periodically , then clearing itself and then resuming normal operation. Then the check engine light began coming on more frequently. It was setting the following codes. P133, P134, P135 and P1133 . I replaced Sensor one, Bank one and now . Still setting codes and the condition is actually worse now. Any ideas where to go next? Chris

 

All those codes are issues with bank 1 sensor 1 o2 sensor. if that is the one you replaced, maybe its bad. You could swap it with one of the other sensors to see......or replace it under warranty.....

 

Yes, I agree. Sensor 1 Bank 1... thanks. I have a code reader.Good idea. Seems unlikely to be bad out of the box but...I'll try that. Possible the part was returned and put back on the shelf. Thanks

 

did you check the 02heater fuse