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        General >> Give/Need advice to/from others >> MOT failed - high emissions
        
(Message started by: Nick_H on May 6^th, 2005, 5:20pm)

Title: MOT failed - high emissions
Post by Nick_H on May 6^th, 2005, 5:20pm

Hi all,

Hope this counts as 'advice to others'...

Had my new 2.3 in for a MOT yesterday: garage phone me up and say, "bad news, it's failed on emissions."

With visions of pound notes flying away on little wings, I ask them to fully test it to see if it's the Cat or the Lambda sensors or whatever else...

An hour or so later they call again and tell me that they have cleaned the electrical contacts on the Lambda sensors (a bit grubby and/or corroded), reassembled and tested and now the emissions are within MOT limits!

So... either this is a useful tip for others to try... ...or it's a load of BS and the garage has just worked out an easy way of charging an hour's labour for doing nothing...

Any opinions?

N_H
:-/

Title: Re: MOT failed - high emissions
Post by craig on May 6^th, 2005, 7:24pm

nick....

on this topic,i have heard,and also know of someone who's car also failed the MOT on emissions,something to do with the cats being cold,after a 10 minute drive up the road,and with the car now fully warmed up,the car the passed with flying colours........
possibly connected...?????

Title: Re: MOT failed - high emissions
Post by nitram on May 6^th, 2005, 10:34pm

I had a car that failed the emissions (Lambda value too high, i think) and was also told that cleaning the lambda sensor solved the problem.
From what I know (Not much!) The lambda sensor returns the results to the onboard computer which will then adjust various things to make sure the emissions are within limits. I guess if the lambda sensor needs cleaning, it may be returning a lower value than expected, so the computer makes the wrong adjustments.

Don't take this as the gospel by any means, I'm nowhere near an engine/exhaust expert. It's just what I interpreted when I looked into this

Possibly another good bit of advice to come from Craig's post is take the car on a good run out before going to the MOT station, to make sure it's well warmed up.

Title: Re: MOT failed - high emissions
Post by Simmo on May 7^th, 2005, 6:22am

I was present at one MOT test and was intrigued to see a probe being placed in the dipstick tube. I was told that it was to ensure the engine was 'up to temperature' as a low temperature could affect the emissions. This seems to make sense and follows the general ideas above.

Title: Re: MOT failed - high emissions
Post by mickf on May 7^th, 2005, 9:36am

My car was up for the test just the other day and was failing the emmissions part on the Lamda sensor - the cause was a slight blow from the exhaust joint on both pipes coming from the Cats - a dab of black stuff around the joints to stop the blowing resulted in a pass on the Lamda reading.

Title: Re: MOT failed - high emissions
Post by admin on May 11^th, 2005, 7:10pm

Although the ECM is quite good at compensating for the O2 sensors aging, they should be seen as a replaceable part after approx 80,000 miles. They are not expensive and easy to change with the correct tools and a ramp.

They have a hard life and new ones made a big difference to mine.

Steve