MOT con or not? | The Back Room Archive | Back Room Forum

Sat 12 May 2001 16:44

MOT con or not? - J E Jones

Forgot that my wife's 1994 Micra needed a test until the last moment so went to a Motest While-You-Wait station. Failed on the Lambda reading - 1.211. Spec is 0.970 - 1.030. CO and HC both registered zero.

Last year the Lambda reading was 1.003 and has never exceeded 1.006 in the last 3 years. They have advised that a new exhaust flow sensor is probably required.

Do you think that they might be charging for unnecessary work and are just out to make money?

Can anyone advise what would be a reasonable price to pay for the replacement work?

Is it likely that a new catalyst at even more expense might be required?

Should I take it to an authorised Nissan dealer since they might have better diagnostic equipment?

John Jones

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Sat 12 May 2001 22:02

Re: MOT con or not? - honest john

Might need no more than a can of fuel system cleaner and an Italian tune up.

HJ

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Sun 13 May 2001 01:18

Pre-MOT "engine tune". - D J Woollard

John,
HJ is likely to be right. A very brisk run to the MOT station just prior to the test can make a huge difference.
Our local MOT tester will send you out for a ten minute drive with appropriate instructions as to driving style, that will mostly bring down the reading within limits to gain a pass.
David

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Sun 13 May 2001 07:12

Re: MOT con or not? - Andrew Moorey (Tune-Up Ltd)

Spot on HJ!

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Sun 13 May 2001 09:19

Re: MOT con or not? - Adam Going (Tune-Up Ltd)

Hi Guys,
Worth mentioning also that just because a car fails the MoT on the "Lambda reading" (which is a computation of emission gasses) it does not follow that the Lambda SENSOR is faulty. The Lambda (or Oxygen) Sensor, which I pressume is what is reffered to as 'the exhuast flow sensor' in this case, is just one input to the management system, and is not the sole contributor to tailpie emissions.
Enjoys your Sunday !
regards, Adam

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Mon 14 May 2001 13:28

Re: MOT con or not? - Vin Kennedy

As a matter of course, I always warm up the car, then run it up and down the local bypass in third (i.e. at around 3/4 peak revs) a couple of times before taking it in for the test. If you've booked at a specific time, you then drive it straight in - the engine's at correct temp and the exhaust has blown through any build up residues. Not had a failure yet.

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