Glow plug light stays on

[Tonykk]

Hi all new to the forum so hello’s all from chilly uk brrrrr.

my daughter has a 2016 a class glow plug light remains on after starting up and stays on when driving. Glow plugs were replaced as she thought they were fault. But no change…

when starting the car in the morning it is a little on the slow side turning over but starts up okay within 5 second.

mechanic who recently serviced it put code reader on but said it’s not saying what’s up and it could be a faulty senor.

any advice would be much appreciated.TIA

 

[whitenemesis]

Glow plugs changed, then next is the relay/control module. Very common failure

 

[Supernoodle]

Change the mechanic too.

 

[Tonykk]

Glow plugs changed, then next is the relay/control module. Very common failure

Thankyou. Is it possible to test this item or just take a flyer and replace it.

 

[boxer 01]

Thankyou. Is it possible to test this item or just take a flyer and replace it.

Not on your particular model but my experience is even after changing the glow plugs if car is struggling to start on cold mornings it's usually the glow plug relay (and I don't think it throws up a fault code). My advice is if you're going to replace use an original one, there's many cheaper ones on the market but won't last as long, believe me I'm talking from experience.

 

[DSM10000]

Thankyou. Is it possible to test this item or just take a flyer and replace it.

You could test for a voltage at the glow plugs.

 

[Smart320]

Don’t mess around, just buy a MB part and replace the controller , that will sort it as long as you haven’t replaced the glow plugs with cheap Chinese parts

 

[zipdip]

Welcome aboard,as above buy a relay,you have changed all the glow plugs,I would have just changed the faulty one,but also I would check the charge going into the battery and the battery itself,regardless of the glow plug light,the A class engine is not big and it should turn over straight away.

 

[ChrisEdu]

Ah this brings back memories!
I had the issue on my W211.
Replaced the glow plugs, light stayed on. Changed the module, light stayed on. Checked the wiring, no issue. Checked the newly installed glow plugs - bingo! One of the plugs had, for some reason, failed catastrophically and warped out of shape!
Replaced busted glow plug - problem solved!

 

[Tonykk]

Update…

relay replaced glow plugs are working. Any other reason the glow plug light stays on please

 

[zipdip]

Well as per my post I normally only change the glow plug that is wrong,so you have changed the relay and the light stays on,you need a multimeter and test the power going into each glow plug you put one lead to earth on the engine and the other to the power at the glow plug you should get less than 6 ohms,it just might be that one of the new plugs has failed.