Over fueling 850 T5

[Craig]

Anybody know exactly how rich the mixture would go if the o2 sensor failed on my t5?, the car has failed its mot on the emissions( runnning at %12!). Having taken the car into a garage they say there are no fault codes logged in the memory but that the o2 sensor is slow to respond and that the front flexi pipe is leaking slightly. Would the leaking flexi pipe affect the reading given by the o2 sensor? I'm not sure it would myself because the exhaust wouldnt pull air in if its running positive pressure would it? I've also been told to replace the cat as its choked up after running rich for so long, however not being made of money and the price of new cats being what they are I dont want to replace it unless I have to.

Given the garages advice do you think these faults would drive the mixture up as high as %12 or could something else be to blame?.

[Guest]

the exhaust is not always positive pressure.

your case is ripe for disaster coz

1) cat is clogged up
2) leak in exhaust b4 cat
3) upon piston withdrawing, sucking in air
4) o2 sensor detects oxygen
5) ecu increases fuel intake.


solve it fast or your O2 sensor will be gone in less than 6 months. more $ will be gone. other solution is do not use car until can cough up dough to repair.