P0420 on 172 ph2

[Or172]

Hey
So i guess P0420 it's cat and not lambada , Right?
Anyways. The main question is if 172 ph1 cat will fit 172 ph2 ?
Thanks !

 

[da rok]

yep that's low cat efficiency...

 

[Or172]

Any chance it's the after cat lambada?

 

[da rok]

the lambdas read the oxygen content, the post cat lambda should be at a steady voltage if the cat is working properly, however if the cat is toast then the post and pre cat voltage graphs will start to look the same indicating that the cat is dead, that will bring up a light (sometimes) if you can, get a obd scanner that does live data and see what the lambdas are reading... it can very well be a dead post cat lambda reading crap or there may be a air leak in the exhaust causing the lambda to sense too much O2...

lambdas do fail, what you could do is get the live data readings, swap the sensors around (pre to post and post to pre) and see if there is any difference and if you still have a fault...