Hello,

I have a problem with the engine warning light being permanently illuminated on my focus st170 53 plate. It first came on soon after i bought the car 2 and a half years ago, I took it back to the garage I purchased the car from. They told me it was something minor fault to do with the engines emissions and turned the light off. Soon after however, the light returned and has remained on ever since! The car drives perfectly well and always has done but last year when I had my MOT the garage told me that the car would fail next year with the light on. Now my MOT is almost due again and I'm planning to sell the car to get something a bit cheaper to run. Either way I'm desperate to get rid of this horrible light and hope it stays off! Please can anyone help me?

Thanks in advance!

If it's on and garage says its emissions related could be the Oxygen sensors in the exhaust if this isn't fixed a new cat be needed my sensor went in my old fiesta was 70 quid for the sensor then labour on top then garage didn't notice my while exhaust hanging off so had to get it welded back on seperate problem though

You won't be able to get the light to stay off without fixing the problem or taking the bulb out.

Unfortunately, taking the bulb out will also get you an MOT fail and any car-savvy people wouldn't touch it with a barge pole as the light is supposed to illiminate for a short time on startup.

Anyway, the problem will be relatively minor. Emissions problems which turn the light and don't affect the running of the car on are generally something to do with a faulty lambda sensor or something like that. It could also be the same problem that I have - my light is currently on due to an evaporative emissions fault - there is a valve which lets evaporated petrol from the tank out into the engine under controlled conditions, and mine is busted and needs to be replaced.

Is there a large suction/depressurising noise when you open your fuel cap? If so, then it's probably evaporative emissions fault like mine, otherwise it'll be a carbon emissions fault due to a lambda sensor or something stupid like that.

The garage who tested it should have told you the fault code when they tested it tbh - rather than just telling you not to worry about it and clearing the trouble code. Get it tested again and find out the fault code first - otherwise you'll have no real clue what really needs fixed.