Emissions MOT failure

  1. My model of MX-5 is: 1.6 (90bhp)
  2. I’m based near:Huddersfield
  3. I’m looking for technical help or recommendations on: emissions

Hi all

I have just had an emissions failure on my MOT. I had a blowing exhaust which has now been repaired but the emissions failed again.

I was told to put in Redex, premium fuel and give it a run (which i did this weekend putting on 400 miles for the anniversary show) .

Just awaiting another emissions test - has anyone any recommendation’s or ways of tuning the car to ensure it passes as servicing these days doesn’t seem to include any tuning whatsover!

Many thanks


Forgive my ignorance but does the car have a cat fitted? Think you have done the right sort of things. Maybe check that the air filter is clean. Run some more premium fuel through it and give it a good “Italian tune” before you present it for its MOT

1 Like

Thanks for the reply! Air filter replaced and service - has cat - failed again - they have offered for me to drive in straight from fully warmed up run - any other ideas would be welcome - things to check before I go in etc. thank you

Which element of the emission test did it fail? What are the readings?

Check the AFM that’s what caused ours to fail a few years back. Also ours is 1990 1.6 and V5 stipulates %CO 3.5 & HC 0.12 I think it is tested differently than it normally would be, others on here will probably know more. Edit … just checked the last MOT and states “Non-catalyst equipped vehicle” even though it has a cat so perhaps you are having the wrong test?

Don’t know this time but first time the hydrocarbon reading was shooting up when revving

It’s 1994 so has a cat - I also have a 1990 model which has a cat and that sailed through - although I’m thinking of removing the cat from that one

High hydrocarbons indicates unburnt fuel, misfire for example. Was that the only failure?

Yes sir

Thanks all - took the car down motorway in 4th holding 4,500 revs for a good few miles - called MOT place to expect my arrival with a warmed up car. Passed