Mercedes CLS Diesel Coil Light Stays Lit

[silversurfer10]

Hello everyone,

When driving my 2010 Mercedes CLS Grand Edition W219 today, I noticed that the diesel coil light came on and stayed lit for around 30 minutes, went off and then came on again. Once stationary, I switched the engine off, started it again and the coil light remained lit.

I was wondering what the issue could be and if driving it for a few days like this before I can see a mechanic would cause any issues in the future? Many thanks in advance.

 

[W1ghty]

Probably a glow plug has failed buddy
No issues driving it

 

[DSM10000]

As above or possibly the Glow Plug module.

 

[Larkone]

There should be a code if a glow plug has gone

 

[DSM10000]

There should be a code if a glow plug has gone

Good point. A good code reader should even tell you which plug has failed.

 

[silversurfer10]

Thank you everyone. Since my post, I have noticed that on some journeys(most of my my journeys are long), the light does not come on at all. Is it normal for the light to come on during some journeys and not on others?

 

[Smart320]

No , should only come on when you turn ignition on for a cold start and it should go out after a couple of seconds when plugs hot ( glowing ) . Should never come on while driving. Probably a duff Glow Plug controller and possible one or more glow plugs as well from my experience. Easier to change everything at once , oh and use MB original parts to avoid issues with cheap E-bay parts would be my recommendation

 

[Diesel Benz]

As above but I'd say the usual sequence is a failed glow plug which then makes the glow output stage (glow plug controller) fail (an internal non-repairable fuse blowing).

Best to change the plug(s) first, then the control unit if necessary. The car is good to drive except extreme cold starts but still better to have the plugs changed soon to avoid seizing.

 

[wongl]

It will be a glow plug as mentioned by several members. However, personally I would leave it if the car starts normally on a cold day (unless it bothers you). This is because glow plugs in diesels can break-off when being changed - so something you want to deal with really.