MOT Emissions fail - again!

[Prudie]

Last year I posted about failing my MOT on emissions, got some good advice, also mechanics from work gave their opinion and result was I bought a new Cat and got it through. Now it has just failed again on emissions at the same garage and they are suggesting first I get a new lambda sensor with no guarantee that will help. My question is why is this fault so difficult to solve?

[top_driver]

well if there is nothing wrong with lambda then it wont help, but a faulty lambda will cause a car to fail on emissions

[tonyav]

Usually a faulty lambda sensor will cause a warning light to come on ( the one with the engine symbol lit up red ).

[Prudie]

Yes that came up last year tony and there is no warning light. See my concern is after a new cat and sensor (which is all a lot of money) and it still fails then the garage doesn't know what it's dealing with.

[TWR]

First, has the car been serviced well? do you go for a run to warm the car up before the test? Every 3rd fill up I purchase a bottle of Injector Clean ( REDX)
& pour this into the tank before filling up, I have never had Emision trouble. what mileage has the car done? Do you use cheap fuel or do you keep to the same?

[johnny37]

I have heard this sort of story many times in the trade. Seems odd that replacing the cat managed to get it through and its now failed again. Ask for your money back on the cat and ask what they intend to do if the new lamda doesnt solve it. Garages cannot charge you for work that they cannot guarantee. They are the professionals, not you.

[tonyav]

Prudie, TWR is right, using some injector cleaner may well solve your problem ( and pretty cheaply ). Do you use your car for short stop start journeys ?, if so i would also recommend changing your spark plugs ( i am assuming that your car is petrol and not diesel ).

[tonyav]

Prudie, i almost forgot it would probably help if you changed the air filter at the same time as the spark plugs.

[TWR]

Just read this Prudie.

Reform
Newbie


Join Date: May 2010
Location: Leicestershire
Posts: 12
Drives: 2002 Sedona
Gallery: 0

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Although I have not used it in my sedona, I have used redex in an old petrol car to clear some crud from the fuel system and it worked at treat after just 3 treatments, after that i used it every 6 months to keep it all clean and never had a problem there after.

It definately wont do any harm if you do as bruno says and ensure u have the right one and at the right doseage. And it may well aid keeping you running smoothly.


06-05-2010, 03:53 AM #4 (permalink)
MCJ

There is one for Petrol + one for derv.

[Prudie]

Just to add some answers/facts:
petrol, 66000 miles, use standard unleaded, usually Tesco's, had a service since last MoT with new air filters, plugs included, the testing garage confirmed they'd run the car up before testing.I've heard of Redx which helps!

The garage have said if a new sensor doesn't do it they will replace the cat free as it's under warranty and after that their only other suggestion is engine management system is faulty but wouldn't that show up in other faults? It drives a dream in my opinion.

[tonyav]

I think that if your engine management system was faulty it would most likely light up the engine management warning light.

[DTCwordfan]

Using Tesco or any s-market fuel doesnt help emissions and sooting - it has no detergency supplements in it - Shell and Chevron have the best fuels for that.....I have seen valves on cars after 5000 miles run on different fuels and the results are startling......and by the way, even though the petrol may be pooled, it is the addition of these forms of additives at each company's loading arms that make the difference....

[tonyav]

Just had a thought that may help. On some makes of car ( Saab is one ) if you disconnect the battery for a time ( say maybe a couple of hours ) it will send the ECU ( which controls the fuel and ignition systems ) back to factory settings. It's worth a try.

[TWR]

Prudie, I'm sure you have Identified your problem, Tesco Fuel, Look at the exhaust outlet ( Back of your car) put a rubber glove on and run your finger around the inner pipe! is it sooty? there's your problem. I would use a good product, I understand in everyone's life we have to save & look for the cheapest, but I'm sure in your car's case it's not working what car have you got?

[DTCwordfan]

my feeling too, TWR......

[TWR]

I'm sure we are all looking for savings DT I'm not rich by any means but I always use the Known fuels & as said, I always add RED X every 3rd fill, it appears to help.

[Prudie]

Ok I've been out with some kitchen roll and yes it came out rich black. Having said that I'd guess 50%+ of my area use the local Tesco for fuel, they can't all be failing can they!
TWR you are very sweet to tell me where the exhaust outlet is :-)
It's a Celica btw.

[DTCwordfan]

Shell and Chevron do not need the redx, TWR, they "overtreat" their additive levels, esp in the detergent....the other problem that Prudie could be causing is not changing her lubricant for some time - bog std lubs can go about 10-12k miles but then a soot build up develops (or once a year)..... Dorset isn't hilly enough to shorten this distance, - living in the depths of Wales would have me saying 8-10...

[DTCwordfan]

poor lub can also affect your fuel economy too - a hidden cost and typically can cause an inefficiency of 10 to 15%!

[DTCwordfan]

old lub can also impact on fuel economy in a hidden way - can be over 10% less distance per litre...! That is pretty expensive to begin with, never mind the lack of detergency in the fuel versus the delta in pump prices.

In the USA Shell have been advertising 5% fuel economy savings over the competition with their Premium - here they haven't had the balls to do so but the savings circa 10% underpin this claim.

[TWR]

I was taking the Izzz when I refered to the Exhaus Prudie " Honest" try using a different garage for your fuel.