Technical MOT Failed: Emmisions - Seicento 1998

[stevie1604]

Hi Guys

My girlfriends Seicento has failed its MOT on the emmisions twice now, after the first failure I was advised to fit a MAP Sensor so done this and put in in for a retest only for it to fail again!

I have been told fitting a new lambda sensor might be the answer but don't want to keep fitting parts and retesting time after time. I have included both emmision readings below, if anyone can help us it would be greatly appreciated.

Testing station said they had the engine red hot, with the fan running, lights on and hrw switch on as this helps with the mapping!

FIRST FAILURE

DESCRIPTION Limits Actual Value


Engine Oil Temperature Min 80 Deg C 80 Deg C OK


Fast Idle Test: FAILED


Engine Speed: 2450-2950 rpm MANUAL CHECK Pass
CO: <= 0.3000% 0.018% Pass
HC: <=200ppm 14ppm Pass
lambda 0.970-1.030 1.273 Fail


Second Fast Idle Test: FAILED


Engine Speed: 2450-2950 rpm MANUAL CHECK Pass
CO: <= 0.3000% 0.260% Pass
HC: <=200ppm 17ppm Pass
lambda 0.970-1.030 1.208 Fail


Natural Idle Test: PASSED


Engine Speed: 2450-2950 rpm MANUAL CHECK Pass
CO: <= 0.3000% 0.017% Pass


Overall Result: Exhaust Emissions Test FAILED

SECOND FAILURE

DESCRIPTION Limits Actual Value


Engine Oil Temperature Min 80 Deg C 84 Deg C OK


Fast Idle Test: FAILED


Engine Speed: 2450-2950 rpm MANUAL CHECK Pass
CO: <= 0.3000% 0.822% Fail
HC: <=200ppm 43ppm Pass
lambda 0.970-1.030 1.144 Fail


Second Fast Idle Test: FAILED


Engine Speed: 2450-2950 rpm MANUAL CHECK Pass
CO: <= 0.3000% 0.010% Pass
HC: <=200ppm 8ppm Pass
lambda 0.970-1.030 1.100 Fail


Natural Idle Test: PASSED


Engine Speed: 2450-2950 rpm MANUAL CHECK Pass
CO: <= 0.3000% 0.009% Pass


Overall Result: Exhaust Emissions Test FAILED

 

[dronenrs]

considering the lambda readings are consistantly high i would say chances are good its lambda sensor

 

[woj]

considering the lambda readings are consistantly high i would say chances are good its lambda sensor

Either lambda, or leaky exhaust. The fact that they did not find a problem with the exhaust does not mean it is not there. I had a CO failure because of a missing Cat, but after that was fixed there was still lambda failure caused by a really bad exhaust connection.

The main question is: how does the engine run? Lambda 1.2 is very high, if that was real (that is, caused by lambda sensor failure) the engine would exhibit poor running one way or the other (IMO). If everything seems tip-top with respect to engine running really start looking for exhaust leaks

 

[RuiG]

Usually I fault emissions fail to lambda sensor of cat. I don't really thing replacing a map sensor without checking those two first would do the trick.

Exhaust leaks, most of them, can be eye spotted. Just look along the line and check for any black areas, where smoke could be coming out and leaving a trail. Try to tighten connections too between the different parts.

 

[levemircento]

considering the lambda readings are consistantly high i would say chances are good its lambda sensor

I would agree with that suggestion too

 

[stevie1604]

I finally got a lambda sensor which I fitted, put two bottles of redex in the fuel tank and took back for an MOT which it PASSED.

The tester did have the engine red hot with the fan running, lights on and hrw switch on to get the emmisions down!

Thanks for all the replies.

 

[jasonh131]

had my emmsions fail up to 13.3 on the CO2