P1137? After Cat Oxygen Sensor?

[96C280]

Have recieved a code p1137 twice. Does this indicate the after-cat oxygen needs to be replaced? There has been no difference in the performance of the car. What exactly does the after-cat sensor do? What kind of effect does it have on performance and driveability.

Somebody said a bad gas cap can cause a p1137?

Thanks.

[Arthur Dalton]

Shorted 02 sensor.

[mbdoc]

The after-cat O2 sensor has but 2 jobs! Main job 99%, is to monitor the catalyst. The other job is to help with fuel mixture adjustment IF the front O2 sensor is not working at ALL.

[96C280]

Thanks.

By getting the p1137 does it mean that only the sensor is bad and not the catalyst? In other words, a bad catalyst would result in a separate code? Thanks again.