My '04 156 JTS Just failed mot on exhaust emissions ideas for a start point please ? - Alfa Romeo Forum
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My '04 156 JTS Just failed mot on exhaust emissions ideas for a start point please ?

Hi there,

My 2004 156 JTS, just failed its MOT on the emissions.

All 3 readings were above permitted.

I would appreciate forum advice on where to start work please?

Many thanks,

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Thorough check of exhaust for leaks. Get a mate to hold a scrunched up rag over the end of the tailpipe while you look under the car and under the bonnet for leaks.

Check all breather and intake hoses under the bonnet for leaks.

Clean MAP and MAF.

Remive spark plugs and check their condition. This will help diagnose if it is a single cylinder giving the problem or something more general.

Read fault codes, note them, clear them and then take it for a drive and see if any return. Take actions on the new codes.

What were the actual readings of the failure?
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Chuck some cataclean in the fuel tank and give it a good run at high revs on the motorway if it hasn't got any obvious leaks.
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The flexi rubber air intake pipe is known to split on the underside just before the throttlebody. Remove it and check it carefully for perishing or splits. If you find any, replace it. This causes duff air/fuel mix and more often than not an emissions failure on the MOT test as well as being down on power.
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all good advice, but a lot of the time just making sure the MOT tester does the emissions the second you drive in with the engine hot.

that and a good italian tune up on your nearest M-way with preferably a bottle of cataclean in the tank as stated in an earlier post.

Good luck.
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I've just used CataClean on my 156 V6 and it seems to do the trick. Slightly lower emissions but i need a whole new exhaust before the mot anyway.
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156 , emissions , exhaust , failed , ideas , jts , mot , point , start

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