Ruined cat

**Tallulah** · 27-06-2017,12:58 PM

Hi, My car failed it's MOT on emissions last year and had a new cat fitted. It's just failed again and they are saying it needs another new cat? They said if it breaks this one then there may be a problem somewhere else such as it's over fueling? What would this be? And why would this happen? Anything I can do to help? Thanks for any advice

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**zollaf** · 27-06-2017,01:07 PM

was the initial fault as to why the cat had failed resolved, or just a new cat fitted and job done.

**Tallulah** · 27-06-2017,01:11 PM

They didn't tell me there was another fault last year. They just said the cat had gone but no reason given. It's an old car and it hadn't had a new one for years so didn't think to query it at the time.

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**zollaf** · 27-06-2017,01:14 PM

its one thing that usually dies because something kills it, often too much fuel. fit a new cat without fixing the fault and the new cat will soon die too. but, all cats have to comply with certain regulations, so it cant be down to a chap nasty one being fitted. maybe it needs a new lambda sensor, maybe its not actually the cat and it just needs a service, dont know without seeing the emissions fail results sheet.

**Tallulah** · 27-06-2017,01:21 PM

I'll see if I can get it and scan it in, I'm happy to do whatever work is necessary just wasn't sure where to start, thanks for your help.

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**Tallulah** · 06-07-2017,11:04 PM

Here is the fail details

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**FLAPPERJACK76** · 07-07-2017,12:07 AM

Did they do a long test on the emissions? There's no engine speed on the data. Was the engine hot enough on the test? Oil needs to be at least 80 degrees centigrade. As i can see the temperature data is also missing on the test. If a vehicle fails the initial emission test then it should be put through the long test which is approximately 180 seconds at 2500 to 3000 rpm as a catalyst is not effective until the exhaust gas temperature reaches at least 600 degrees centigrade. Some garages just do the initial emission test and fail it through either stupidity, laziness or a sheer desire to make easy money.

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**FLAPPERJACK76** · 07-07-2017,12:14 AM

Also within vcds measured values iirc channel 32 and fields one and two you should be able to read fuel trim readings, if you have the means to do that then post your readings.

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