Just had my pre cat replaced after getting the P0431 code, I told them to replace the left front pre cat near the manifold. Car ran great for a while, then started running rough again and the the CEL light came back on after about 100 miles. Just to check, it's not possible that they replaced the wrong cat is it? Would the one on the left front fit on the right? Also I'm pretty sure it was a bolt on cat(no welding involved) but is also possible that the conenction is loose somewhere and air is leaking out, throwing the code?


On another note, my rear passenger side door is starting to make that dying cat noise when I lock the door(very annoying). I'm thinking the door lock actuator is dying. Anyone got a part # for it? Also, how hard/easy of a fix is it?

 

That would be the one before the radiator. The o2 sensors on alot were overly sensitive and popped that code. A half decent scanner will allow you to monitor the o2 sensors while they operate to see. Normal operation of an o2 is 5 to 7 seconds switching time.