NCT Failure
- Thread starter PatrickBuzzin
- Start date
Keadeen
Well-known member
Hi Patrick, Those values mean it is running really rich.
Did it pass last time - and did you make any changes like exhaust / ecu map etc?
Three most common things I'd check:
1. exhaust still same as before (if passed before and no changes then ignore this one)
2. Check connectors on MAF/MAP and Lambda sensor and check values again (live data in ecu vs actual readings)
3. Either the Lambda, or MAF is not working correctly anymore and needs changing... rather than throw parts at it... read out the values it sees (both voltage and value) on those sensors and go from there to narrow it down to the failed sensor.
Did it pass last time - and did you make any changes like exhaust / ecu map etc?
Three most common things I'd check:
1. exhaust still same as before (if passed before and no changes then ignore this one)
2. Check connectors on MAF/MAP and Lambda sensor and check values again (live data in ecu vs actual readings)
3. Either the Lambda, or MAF is not working correctly anymore and needs changing... rather than throw parts at it... read out the values it sees (both voltage and value) on those sensors and go from there to narrow it down to the failed sensor.
Cheers lads, where would be the best place to pick them up? Back to genuine Subaru or are there others?
Any good motors would be able to get fir you just make sure its denso as that's what will be coming out of it
Sorry guys car was away to get a few bits done. Brought it to another local mechanic who has confirmed that it needs a few small bits but also def needs a cat. Have been onto Cobrasport about their decat system to see if it will pass out NCT so they are checking it out. Have any of you guys put on a decat system or sports cat and how does it fair out with the NCT emissions. On a side note finally got the car back after the wife’s mishap and respirated and fitted the new Revolution Millenniums.
Sorry meant to say they are checking the sports cat option not the decat.
My twin scroll has passed the last few NCT's with a 200 cel sports cat.
Hi Patrick
From memory cobra one i went to order years back was 100 cell wouldn't be good enough for here (uk emissions less strict) 200 cell rcm sports cat passes every year.
If you stick to 200 cell cat should be fine or try get loan of factory one just for test.
A exhaust specialist in your area might be able to sort it too
From memory cobra one i went to order years back was 100 cell wouldn't be good enough for here (uk emissions less strict) 200 cell rcm sports cat passes every year.
If you stick to 200 cell cat should be fine or try get loan of factory one just for test.
A exhaust specialist in your area might be able to sort it too
Keadeen
Well-known member
Hi Patrick,
I have a Cobra sports cat (SB26 was the order code and is a 200 cell... they do not sell a 100 cell as it would not pass with certainty. Note: I see on their site now that today that's a 3" connection, whereas when I got it it was 3" pipe with reduction to a 2.5" centre connection, which is what I got as wanted to stay 2.5" to the back). Passed first two years' NCT with flying colours - every bit as good as the oem cat.
However, on the 3rd year it didn't pass.
1st thought was a lazy lambda (the one fitted in the cat pipe).
Replaced that and still same issue (and was expensive to replace lambda hence my earlier comment above about being certain a sensor has failed through measuring it, rather than just throwing money at replacing them when they might be absolutely fine).
Swapped to the oem cat and problem solved for the NCT... so the Cobra cat failed (not sure if pinprick air leak related to wrapping... possible but unlikely, or else just failed substrate effectiveness). Item was out of warranty so they wouldn't do anything to help even with a reduction on a replacement. Mind that they list "life-time warranty" on their site, but this is only for anti corrosion on the Stainless steel and workmanship, on Cat functioning they only give 2 years as further explained in T&C small print.
What I liked about the Cobra cat is that the fitment is standard (unlike for example RCM), so less hassle if fitting other bits of exhaust system so you're not tied in to one brand. Obviously didn't like it quitting on me by year 3 and relatively few miles (maybe 17k miles). Got a quote from the exhaust place in Rathcoole to cut out cat and replace it with the premium Magnaflow version for 250-300 (using the Cobra downpipe I still have).... so... maybe a similar path might be good way to go for you (to use existing downpipe and have a good sports cat welded in). Definitely can say the sports cat wakes the car up compared to having the oem one fitted... but you must have the car mapped for the sports cat as it will kill your engine otherwise as flow much more than standard.
I have a Cobra sports cat (SB26 was the order code and is a 200 cell... they do not sell a 100 cell as it would not pass with certainty. Note: I see on their site now that today that's a 3" connection, whereas when I got it it was 3" pipe with reduction to a 2.5" centre connection, which is what I got as wanted to stay 2.5" to the back). Passed first two years' NCT with flying colours - every bit as good as the oem cat.
However, on the 3rd year it didn't pass.
1st thought was a lazy lambda (the one fitted in the cat pipe).
Replaced that and still same issue (and was expensive to replace lambda hence my earlier comment above about being certain a sensor has failed through measuring it, rather than just throwing money at replacing them when they might be absolutely fine).
Swapped to the oem cat and problem solved for the NCT... so the Cobra cat failed (not sure if pinprick air leak related to wrapping... possible but unlikely, or else just failed substrate effectiveness). Item was out of warranty so they wouldn't do anything to help even with a reduction on a replacement. Mind that they list "life-time warranty" on their site, but this is only for anti corrosion on the Stainless steel and workmanship, on Cat functioning they only give 2 years as further explained in T&C small print.
What I liked about the Cobra cat is that the fitment is standard (unlike for example RCM), so less hassle if fitting other bits of exhaust system so you're not tied in to one brand. Obviously didn't like it quitting on me by year 3 and relatively few miles (maybe 17k miles). Got a quote from the exhaust place in Rathcoole to cut out cat and replace it with the premium Magnaflow version for 250-300 (using the Cobra downpipe I still have).... so... maybe a similar path might be good way to go for you (to use existing downpipe and have a good sports cat welded in). Definitely can say the sports cat wakes the car up compared to having the oem one fitted... but you must have the car mapped for the sports cat as it will kill your engine otherwise as flow much more than standard.