New Exhaust Failed MOT?

Sarahjovi

Hi,

My mums car has failed its MOT on the Exhaust Emissions, the exhaust is a month old with a catalitic converter. The tester said the exhaust might have the wrong probe in it, but the Exhaust garage says the MOT station are talking rubbish and there is nothing wrong with the exhaust!

The car is a Citreon AX (12 years old).

Can anyone offer any advice!

Thanks

Sarah

Labman_2

Could be the Lamda sensor (Sp.?)...which isn't strictly speaking part of the 'exhaust'.

Sarahjovi

Is that part of the exhaust? or separate?

Thanks

sarah

steveo3002

its a seperate part that is fitted in the exhaust...it sniffs the fumes and ajusts the mixture on the engine to suit when working right

Sarahjovi

So is it down to the exhaust fitters i.e. a part that should have been replaced with the exhaust or would they have re-used the old one!

Thanks

Sarah

gareth12_2

no the garage didnt need to change it, along the exhaust there is a hole where this o2, lambda sensor fits. it can cost a fair amount of money. maybe the mot centre never let the engine warm up enough as it needs to be hot to work properly

cajef

The exhaust emissions are nothing to do with the exhaust, they are dependant on the way the engine is tuned, the exhaust cannot change these settings.

The Lambda sensor is usually fitted in the manifold or front down pipe, and would not normally be renewed with the exhaust system. It monitors the exhaust gasses and feeds information back to the engine managment system to control the fuel mixture, if this is faulty then the emissions test would fail, it is only one of several reasons why the car could fail on emissions, maybe the engine needs a service and tune up.

steveo3002

could be any number of sensors on the engine causing it, the o2 sensor is what was affected by the dodgy tescos fuel

Sarahjovi

Hi, Just an update. Mum took her car back to the MOT garage for them to fix a couple of other items, and they re-tested the emissions and let the car run a bit longer and it was fine and passed the test. Its a shame they didn't do that in the first place!:mad:

Thanks for your help!

Sarah:D

ohreally

cajef wrote: »

The exhaust emissions are nothing to do with the exhaust, they are dependant on the way the engine is tuned

How does one tune an engine that is electronically controlled?