My son has a Ford something or other but he's asked me to book it in for an MOT over Christmas (when he pays his annual visit) but I think the EML is stuck on. I know there are a few on here who know about MOTs so the question is will it mean an automatic failure if it's on, I know lights for ABS etc are automatic failures but that is probably because there is an underlying cause that might be dangerous - it's actually been on all year as it came on just after the last MOT . Geoff

Yes.

MC

Not sure it is a fail as last year my EML came on just before the mot and it was an advisory and still passed.

The EML is not a testable item. It's not mentioned in the testers manual though, dependant on the tester, could bring an advisory.

It's what causes it to be on which could bring a failure, usually emissions, like an O2 sensor.

Right I'll get it booked in with the light on, if there is something else wrong I'm happy to have it fixed but that light has a mind of its own. I just wanted to be sure it would fail just because the light came on.  Geoff

Don't suppose you know what's causing it to light up?

Just that, if it's something minor, it may be prudent to reset it before it makes it's annual jaunt.

Try giving the MAF a clean. That may help the air intake quality and thus the o2 levels. Not sure how to reset the eml on a ford tho?

If it is driven by devil juice then it could be the EGRV stuck open. Previous cars:
S-Max 2007-2013 (only diesel I've had, good car but expensive when diesely bits go wrong, so what's the point?)
Galaxy 2001-2007
Mondeo Estate 1997-2001
Sierra Estate 1993-1997
Uno Turbo 1987 -1993
Fiesta 1984 - 1987
Fiat 127 1982 - 1984

Thanks guys - its Petrol (I don't know if "devil Juice" is petrol or diesel ) but I think I need to clean the MAF on my RR (also petrol) because it runs a bit lumpy on starting but is otherwise OK (not bad for a RR) Geoff

Just asked the tester when I booked it in, EML being on is not a fail of itself, however underlying cause might be  Geoff

EML is usually caused by a sensor going down, which in turn mucks up the fuel mixture.. basically the engine goes in to rich mode.. this will more than likely naff up the emissions and will undoubtedly use more fuel... not much of an issue if it's powered by an engine that wouldn't look out of place on a lawnmower... bit more of a problem when the car is a gas guzzler to start with  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

It's in tomorrow so I'll keep you posted. Geoff

Yep passed no problem, EML on when I took it in, mechanic explained that the problem might be something to do with variable valve timing but passed with no advisory. Emissions etc obviously OK Geoff

Result

Nice Christmas present from your FF  2017 4.4 SDV8 Autobiography
2012 4.4 TDV8 Westminster - Gone, but not forgotten