2.5 Wrx emissions fail

Colmr555

Colmr555

Member
hi all

2.5 wrx in for nct Sunday and failed on high CO on both high and low idle

Sports cat down pipe and standard secondary cat in place - 2 piece down pipe in 06 wrx.

Passed first time last 2 years.

Previous owner DUFFMAN changed front lamda sensor in 2018 ( denso dox 0537)

What would you all recommend I do ?

I want to change all gaskets and bolts from cat back as some are badly corroded and not sure are they sealed 100%

Any other ideas to get me through ?3EE1362B-9571-4B79-AEEA-C548EFC4F673.jpeg
 
i had the same problem and eventually got it through.... replaced both sensors and mechanic put in a generic cat but it just scraped through.... he said they spent ages in the nct centre on the car and only he was in there with the car they prob would have failed it.
 
Where'd you buy the sensors Ed ?

were they denso or other brand ? denso is the oem manufacturer im pretty sure
 
Replaced both sensors as they weren’t over expensive and I wasn’t arsed going back a second time if I only changed one.

Low and high idle CO both came down but high idle is still outside the limits.

What’s next step, try a different catalytic converter ?

Anything else I can try ?

Appreciate any help. Thanks.
 

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Colmr555 said:
Replaced both sensors as they weren’t over expensive and I wasn’t arsed going back a second time if I only changed one.

Low and high idle CO both came down but high idle is still outside the limits.

What’s next step, try a different catalytic converter ?

Anything else I can try ?

Appreciate any help. Thanks.
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I think youll have to go with the CAT change... my mechanic put in a universal one, still just scraped through but worth a shot..... he did mention there was a local guy who was loaning people a wrx CAT just to get through NCT but some other guy had it.... the proper ones are very expensive.... after that its bribe time :LOL:
 
Seems very high with new sensors . Are you running booster or anything in the petrol .

You might need a Center cat aswell to get it below the threshold

Sorry just looked above and it’s a sports cat . You may swap for a standard Subaru cat and it will pass then . The sports cats pass for the first few years and start go get a little worse then
 
scoobysub said:
Seems very high with new sensors . Are you running booster or anything in the petrol .

You might need a Center cat aswell to get it below the threshold

Sorry just looked above and it’s a sports cat . You may swap for a standard Subaru cat and it will pass then . The sports cats pass for the first few years and start go get a little worse then
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Thanks for the replies guys.

@scoobysub should the sensors have made a big difference seen as the lambda was in range the first time around anyway ? sorry just getting my head around this craic never had one fail before.

I think youre right even though i have both cats, the sports cat in the downpipe could be letting me down.

getting the loan of a friends standard sti cat which passed test last year.

Will post how i get on.

Thanks again
 
I had this issue with one of the lads WRX’s, I’d to replace his sports down pipe with a standard downpipe and it went through no problem on both low and high idle. Seems to be the only way of getting them through
 
BazGF8 said:
It’s difficult to get them to pass with a sports cat ,
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I’d never an issue with both of mine Baz to be honest, not 2.5 but a decent sport cat is what it does!
(Zero/Sports)(HKS)

Only issue I ever had once, was the air fuel lambda right at the mouth of the down pipe (sport cat)
Replaced for new about 8 years ago… washed with NF… and no issue 👍🏻
 
Standard downpipe and secondary cat and it passed on the 3rd attempt.

Last slot of the day and tester was very sound stuck with it until it came in under.

Was well below tolerance in the end up.

Thanks to everyone for their advice.

Not looking forward to doing it all over again next year :ROFLMAO:
 
Colmr555 said:
Standard downpipe and secondary cat and it passed on the 3rd attempt.

Last slot of the day and tester was very sound stuck with it until it came in under.

Was well below tolerance in the end up.

Thanks to everyone for their advice.

Not looking forward to doing it all over again next year :ROFLMAO:
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Great stuff, unfortunately you will have to fit standard exhaust system for nct each year , enjoy it now 👍
 
Colmr555 said:
Standard downpipe and secondary cat and it passed on the 3rd attempt.

Last slot of the day and tester was very sound stuck with it until it came in under.

Was well below tolerance in the end up.

Thanks to everyone for their advice.

Not looking forward to doing it all over again next year :ROFLMAO:
Click to expand...


A scenario we all have to deal with going forward unfortunately , Glad Youre sorted :thumbsup:
 
Just leave the cats in them as standard 🤪🤪🤪🤪🤪🤪🤪🤪🤪🤪🤪🤪🤪🤪🤪

Congrads on the pass 👍👍👍sorted for another year . It’s getting a bit harder each year to pass I think
 
Colmr555 said:
Standard downpipe and secondary cat and it passed on the 3rd attempt.

Last slot of the day and tester was very sound stuck with it until it came in under.

Was well below tolerance in the end up.

Thanks to everyone for their advice.

Not looking forward to doing it all over again next year :ROFLMAO:
Click to expand...
good stuff Colm, its almost as bad as going to the dentist going for a dam NCT .... at least you have a year on it now...
 
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