Code P1131 on 2000 GT question

If you can, get under your car and check the connectors, two on each side. Upstream sensor is between the cat and motor, downstream is after the cat. Clear your codes to see if they come back.

All the connections look OK. I had a friend with a fancy ODB laptop check the output when the engine is idling. One of the front O2 sensors has a jagged sine wave output on the graph (while the others are smooth). He said the sensor may just be doing its job and the problem may be elsewhere. I may swap the sensors from left/right in a few days to see if the problem is with the sensor itself. (It's a bitch to get to the front ones even when the car is on the lift). Other things I'm going to try is to spray the MAF again and check the PVC valve.

All the connections look OK. I had a friend with a fancy ODB laptop check the output when the engine is idling. One of the front O2 sensors has a jagged sine wave output on the graph (while the others are smooth). He said the sensor may just be doing its job and the problem may be elsewhere. I may swap the sensors from left/right in a few days to see if the problem is with the sensor itself. (It's a bitch to get to the front ones even when the car is on the lift). Other things I'm going to try is to spray the MAF again and check the PVC valve.

some of that spray stuff can mess up an O2 sensor some gasket material used on intake can mess it up too. should say on the can or tube if it gets the O2 sensor. bank 1 is probably one side of the car Jagged is not good, check for loose connections or corroded connections. could be bad/cracked sensor too should be like a soft square wave about 1/2 volt high no jagged stuff. It is counting time between zero crossings, and a jagged if too deep/high will give false info to computer. Swapping is the right thing to do, then see if the problem follows the swap or not. good luck let us know what happened