Hey all i had my cat replaced on the car few months ago, since then i can hear a hissing type noise when accelerating next to buildings. I thought it was just a leak in the exhuast (dodgy welding). Took car back they couldnt find any leaks so they thought it could be a dodgy cat or muffler.
Whats worrying me is could it be my cat blocking up again? I extracted fault codes seems that i got a code 133, Upstream Heated Oxygen Sensor circuit Slow Response - Bank No. 1. So does this mean my oxygen sensor is stuffed, and causing my CAT is block up again???
I checked my plugs today, on the tips they are grey, which means the car is leaning out. I think my car is down on power as well.
so do these symtoms relate to a stuffed oxygen sensor?
Might be your injectors. I don't have anything on EL error codes, but I'm guessing that means either one of your injectors in bank one is rooted and causing the HEGO sensor to think it's running lean, or the injectors are on the way out and bank one happens to be below standard while bank 2 is still above.
I'd most likely say one of the injectors is gone. If the HEGO sensor was to blame the ECU would eventually learn it was faulty and run accordingly, giving you your power back. One rooted injector would cause the whole engine to loose a bit of power.
However grey plugs would point to all the injectors being on the way out.
As for the hissing, can't help you there, though it might be related.
Sounds like fuel delivery if it's across all injectors. Might be time to check out the fuel pump, fuel hose, and regulator?
Probably a better idea - does she idle high? Those symptoms could also be caused by an intake leak, which would also explain the hiss.
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