Technical failed mot emissions

Currently reading:
Technical failed mot emissions

seanhyde

New member
Joined
Dec 12, 2011
Messages
112
Points
25
Location
dorset
Hi MOT time so here starts the fun! 1.1 seicento failed emissions mot states
1. Exhaust emissions Lambda reading after second fast idle outside specified limits.
2. Exhaust emissions carbon monoxide content after 2nd fast idle excessive.
They did not give me a reading ?
The engine management light is on permanently? I'll borrow a reader tonight and get the code.
MOT man seems to think I should replace CAT, service car and have another go. Seems an expensive shot in the dark.However it is a 2001 and still has original CAT.I changed the exhaust about a year ago.
Any ideas or suggestions would be appreciated
Thanks
 
You can get this addative which cleans the cat usually gets your through an mot i know alot of vauxhall owners that live off the stuff cant remember the name though
 
Does sound like cat but with the eml on it could indicate that it's over/underfueling because a sensor is down or whatever so would def scan it first before doing cat
 
Thanks all
I'm waiting on my mate to borrow his code reader so will post results of this before I proceed. Dave the thing about getting it really hot. Last year ther was a problem with emissions at MOT.The garage ran the car till it overheated ! A few weeks later Head gasket went ( again! ). I came into the garage as they were doing the emissions test and requested he not over rev it for too long in case it overheated again ! Should I have let him carry on? This was the second test the garage tried !
Also seeing as it is a 2001 model ,how long should a CAT last ? would it be reasonable to assume that 13 years was about it before a CAT would start failing anyway? The car is a !.1 and has done 80,000 miles
Cheers
 
Last edited:
Get a tank of Vpower in, the stuff you can buy is called cataclean, but get some high octane through it and a motorway run or 4/5000rpm up a hill with the throttle pinned get the cat glowing, ours just scraped past after we bought it, I fitted DENSO iridium spark plugs a k&n panel filter, it's runs on Vpower and 2degrees of ignition advance and it goes like stink and sailed emissions this time :)
 
Answering my own question the AA state

How long should a catalytic converter last?
Catalysts often last 10 years, but actual life depends on mileage and engine tune. 50,000 miles is a more reasonable benchmark, and you can generally expect to replace the catalytic converter once during the life of a vehicle.

If failure occurs early, it's important to find and fix the cause of the problem before fitting a new CAT otherwise the replacement can be expected to fail prematurely too.

There are three main ways they fail:

Melt down - unburned fuel enters the catalyst and ignites on contact. The extreme heat literally melts the ceramic matrix. Poor ignition timing, a faulty oxygen sensor, worn or defective spark plugs, incorrect fuel mixture and other ignition/fuel injection related faults could lead to this failure.
Carbon deposits - oil or antifreeze entering the combustion chamber/exhaust system can lead to a build up of carbon on the matrix, which increases back pressure leading to overheating and poor performance.
Catalyst fracture - the ceramic matrix is fragile and can break-up as a result of excessive vibration or external impact. As the matrix breaks up back-pressure increases and overheating can result.

Does anyone have experience different to this ? I'm the second owner and I know I have the original CAT
 
Thanks all
I'm waiting on my mate to borrow his code reader so will post results of this before I proceed. Dave the thing about getting it really hot. Last year ther was a problem with emissions at MOT.The garage ran the car till it overheated ! A few weeks later Head gasket went ( again! ). I came into the garage as they were doing the emissions test and requested he not over rev it for too long in case it overheated again ! Should I have let him carry on? This was the second test the garage tried !
Also seeing as it is a 2001 model ,how long should a CAT last ? would it be reasonable to assume that 13 years was about it before a CAT would start failing anyway? The car is a !.1 and has done 80,000 miles
Cheers
it shouldn't over heat unless there is some thing wrong with it, let him rev the crap out of it. cats dont work unless very hot, a new one will need running in by revving hard too
 
Last edited:
Anyone used this Cataclean stuff ?
GrandeGuy that link took to me to a sports CAT.What's that about? It's stainless. My CAT is attached to the manifold, its all in one.Where would this sports CAT fit in?
Thanks for replies
 
will do . I can't get hold of mates reader till tomorrow after work,so have to wait. Just ordered myself one off ebay as they seem pretty cheap now.
Thanks
 
Code update
P0300 random misfire
P0351 ignition coil A primary circuit
now the old p0300 has kept appearing since owning the car. As some of you know I've done the head gasket 3 times! in the last few years and last time replaced with a good head from fingers. I've also replaced both coil packs packs a year ago along with the HT leads. Am I heading for another Head gasket failure ?
And does this help understand emission failure. Or could an old CAT be causing the codes ? Help

Also I have an old but little used Gunsons Gastester proffessional CO tester ( a bit of DIY kit) .Following the instructions carefully I get a CO reading of between 0.2 and 0.5. It seems to jump a round a bit. I don't know if this helps or not.
 
Last edited:
The main way heads go is overheating, has the radiator and water pump been checked or replaced? May be worth doing the temperature guage mod also to keep eye on tempt if not done already.
 
I'd not think the HG is the issue -- unless there are other symptoms -- or the CAT. That's the good news. This based simply on the codes.

Any car with a misfire is going to fail the MOT emissions big time: generally you'll be pumping a fair bit of fuel straight out of the exhaust even after the poor old cat has had a go at it. .

If you're lucky, the fault (P0351) may be no more than a poor connection to the primary side of the coils (from the ECU). So check the pop in connector for cleanliness, clean up the contacts, smear a little silicone grease on them, trace the wiring back checking for worn through insulation, etc.

If you can clear this fault, you may find that P0300 disappears, too.

If it doesn't, and you have the micro ECU, the bad news is that P0300 is often associated with ECU failure. In the Punto guides there's a good one on testing the ECU (fundamentally, the Punto 2 ECU is the same as the mid-period Sei ECU with the addition of canbus, which doesn't concern us here).
 
One other observation. I fitted a new exhaust about a year ago. all looks pretty new and shiny still however there is black soot along the pipe from a number of the joins. Is this normal or does it suggest gases escaping and could this be part of the problem?
an edit to this .The exhaust is definately not sealed properly at the joints in two places !
 
Last edited:
Black soot on joins would suggest gases excaping won't be it I wouldn't have thought. Another thing to look at would be if when the hg went in the past and lots of coolant has been burnt then this can sometimes foul the lambdas worth a try do have some good ones here if you need it or pop over if your not too far. Do the codes reappear once cleared any running issues?
 
Thanks for that . I often drive through illminster so if things start to point to lamda that offer sounds good. Still seems a good idea to seal up exhaust joints.
 
Back
Top