Hi all,

just joined this site and I’m after so advice about emissions as I have no ideas about them. My 58 reg fiesta failed it’s MOT on emissions today but don’t k ow what needs to be done to get it passed.

garage said it could be a few different things, exhaust/cat converter, oxygen sensors, valves I think he said too.

Had the garage take a look at my Cat and said they would have to remove drive shaft to replace it. Costly job by the sounds of it!!

Is there any cheaper ways to improve emissions to get it through.

CO was at .47% on second fast idle test

Lambda 1.05 on first fast idle test

like I said not got a clue!!
 

May we have some more info ?

Petrol/diesel, how many miles has it done, is it a late 02-08 model, or an early 08 onwards ?

It’s a 1.2 petrol. 91,000 miles. I know the car was registered in 2008 but I didn’t purchase it till early 2009. Hope that helps

That's an odd set of results.  The lambda reading is showing a lean mixture (too much air).  But the excess CO suggests you've got too much fuel.

I would suspect a leak on the exhaust system (past the engines lambda sensor) for the dodgy lambda reading with the probe.

Excess CO could be a faulty cat, their efficiency at converting CO to CO2 drops over time.  However, personally I'd stick a new set of spark plugs in, give it £20 of premium fuel and then give it a good thrashing.  Take it to the MOT centre hot and get them to retest after that.  Considerably cheaper than replacing the cat if it works.

Is that what we used to call an "Italian Tune Up" ?

2 hours ago, TomsFocus said:

That's an odd set of results.  The lambda reading is showing a lean mixture (too much air).  But the excess CO suggests you've got too much fuel.

I would suspect a leak on the exhaust system (past the engines lambda sensor) for the dodgy lambda reading with the probe.

Excess CO could be a faulty cat, their efficiency at converting CO to CO2 drops over time.  However, personally I'd stick a new set of spark plugs in, give it £20 of premium fuel and then give it a good thrashing.  Take it to the MOT centre hot and get them to retest after that.  Considerably cheaper than replacing the cat if it works.

I know I am behind with my services too. Would putting new air filter, fuel filter help also??

1 minute ago, Poom said:

I know I am behind with my services too. Would putting new air filter, fuel filter help also??

Probably not unless the air filter is very old.  They last much longer than garages would have you believe.  It is a cheap and easy part to swap yourself though so no harm in trying it.

If it's a Mk7, there is no fuel filter to change.  (2008 was crossover so we can't tell by year alone)