Check Engine light - MOT fail?

[paulfoel]

Been on since I had to jump-start the car which I understand can happen on the merc. (BTW - its a 2001 A160).

Bought an OBD reader off ebay and there was a fault code. Managed to clear this. Trouble is today its back - first time I used the car.

Couple of questions:-

1. Is Check engine light an automatic mot fail?
2. Should I be able to clear the fault or do I need a proper code reader to do this?

 

[lexman8]

1. Is Check engine light an automatic mot fail?

My understanding is that it is now an MOT fail as it may indicate a problem with the emission control system.

Should I be able to clear the fault or do I need a proper code reader to do this?

I've managed to clear a Check Engine light using an OBD reader. But that was a transient fault. If you have a 'hard' fault the light will keep coming back on until the problem is fixed.

 

[TegTypeR]

What is the code?

Have you identified it yet?

 

[RoDDDimuS]

Been on since I had to jump-start the car which I understand can happen on the merc. (BTW - its a 2001 A160).

Bought an OBD reader off ebay and there was a fault code. Managed to clear this. Trouble is today its back - first time I used the car.

Couple of questions:-

1. Is Check engine light an automatic mot fail?
2. Should I be able to clear the fault or do I need a proper code reader to do this?

to answer you questions

1) your car will not fail an MOT on an engine fault, unless, that fault is causing poor emissions or there is something unsafe or insecure.

2) The engine management light will come on to notify you of a fault and stay on until you clear it. If you clear all you are doing is saying to the computer right the car should be ok, but if you havent fixed the actual fault it will come back on

 

[sallison1504]

If they can see the light is on it will fail. If they can't see the light is on, they can't fail it, unless it does actually fail the emissions test. The example is, if you put tape over the light, so they can't see the light, they cannot fail you. They also are not allowed to remove the tape, as they cannot tamper or change anything on the car, as it could constitute fraud on the results of the test.

 

[jaymanek]

As well as ABS and traction system lights, these are the ones tested at present.

Headlight main beam warning light
Electronic power steering warning light
Brake fluid level warning light
Seat belt pre-tensioner warning light

Engine warning lamps arent tested.

 

[paulfoel]

After some research it seems some of your are right. You don't fail because of a check engine light - only the ones jaymanek mentions.

Of course, if the check engine light causes something else like emissions fail thats different. But yes, I agree what everyone says.

I thought the light was just due to battery issue but it appears not. I'll check again when I get home tonight.

Sallison - I dont think you're right there. If its one of the lights listed then you'll fail simply by having a non-working indictor surely? It'd be like having a wing thats so rusted its falling off but then wrapping it in bin bags to the testers cant see it.

 

[sallison1504]

After some research it seems some of your are right. You don't fail because of a check engine light - only the ones jaymanek mentions. Of course, if the check engine light causes something else like emissions fail thats different. But yes, I agree what everyone says. I thought the light was just due to battery issue but it appears not. I'll check again when I get home tonight. Sallison - I dont think you're right there. If its one of the lights listed then you'll fail simply by having a non-working indictor surely? It'd be like having a wing thats so rusted its falling off but then wrapping it in bin bags to the testers cant see it.

If they can't see the light, they cannot fail you. It would be like taking the bulb for the indicator out of the cluster. The MOT tester is not going to take the cluster out so they can check all of the bulbs. If the light is not on or they cannot see it, they cannot fail you, unless it's obvious IE, emissions.

 

[paulfoel]

If they can't see the light, they cannot fail you. It would be like taking the bulb for the indicator out of the cluster. The MOT tester is not going to take the cluster out so they can check all of the bulbs. If the light is not on or they cannot see it, they cannot fail you, unless it's obvious IE, emissions.

OK but surely for something like an ABS light which is tested, they all come on when the ignition is switched on (to test them!) so they'll fail you on that. Seems obvious to me?

 

[paulfoel]

OK. The fault is P0100 Mass or Volume Air Flow A Circuit.

Any ideas?

 

[DSM10000]

If they can't see the light, they cannot fail you. It would be like taking the bulb for the indicator out of the cluster. The MOT tester is not going to take the cluster out so they can check all of the bulbs. If the light is not on or they cannot see it, they cannot fail you, unless it's obvious IE, emissions.

If certain warning bulbs / lights are not shown / illuminated in the cluster then that is a fail.

See here for a list of items checked and what constitutes a Pass / Fail:MOT Test Checks List - MOT Testing Industry Portal