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Exhaust Emissions...

1.2K views 7 replies 5 participants last post by  13OB  
#1 ·
Hello!

I've got an exhaust emissions light on my dash.
I get the Error P0420 Catalyst Efficiency Above Threshold C-31.

Someone then said:

"new manifold time cats fecked"

A mate suggested it's probably one of the sensors (Lambda)....
I thought it couldn't be what the first person suggested as the car passed it's MOT yesterday, so it had to pass an emissions test?

Any other suggestions? The light is more irritating if anything.
The car doesn't seem to perform any different with or without the light.

HELP! :)
 
#2 ·
Anyone?!
 
#3 ·
I get it all the time, just means the lambda sensor has had a reading above/below the limits set by vauxhall. Just ignore it, it should go off everytime you turn off the car so makes no difference. And if it's passed an MOT there's definitely nowt wrong
 
#4 ·
I get it all the time, just means the lambda sensor has had a reading above/below the limits set by vauxhall. Just ignore it, it should go off everytime you turn off the car so makes no difference. And if it's passed an MOT there's definitely nowt wrong
with an aftermarket exhaust yes....

however if it standard it is most likely to be a faulty sensor :) think the most common one to go is the post cat sensor but i could be wrong, sure some boffin can tell you which it is from thew code mate
 
#6 ·
Cheers lads appreciate the replies.
Yeah I hope it is a sensor cause if it's the cat, I'm screwed!
My warranty just ran out aswell, I don't mind paying for it.
The light is bloody annoying though.

Much appreciated!!!!
 
#7 ·
When you say with an aftermarket exhaust it's all good, do you mean a full aftermarket exhaust system or just the back box? I have exactly the same problem as the original post (MoT pass, no noticeable drop in performance but the exhaust emissions light still on) and also have an Irmscher back box? Is this normal?

Cheers