Glow Plugs Dashboard Light

[JBH1488]

Good afternoon everyone,

So a few weeks ago by battery decided it had had enough and packed in. The RAC came out, he checked the car over, diagnosed the battery was infact dying and was only operating at about 1/4 of what it should be. So he jumped started the car and asked me if the glow plugs dash light was on before and I told him it wasn't, so he removed the fault code for it anyway. He tried selling me one of their batteries at £255 a pop, to which I kindly refused and told him I'd just pop to Halfords. He gave me advice, told me that it will be the 115AGM that I will need.

So off I went. Halfords only had 096AGM and the guy assured me that this battery would be absolutely fine. So the battery got fitted, I drove off and the next morning the glow plugs light was back on.

By this point the car was already booked in for its MOT and full service. They tried replacing the glow plugs relay and the glow plugs and this didn't fix the issue, which they were honest enough about and didn't charge me for the parts they'd ordered in and tried on the car.

Does anyone have any idea what the possible cause could be? The garage themselves didn't see too sure and just recommended taking it to Mercedes which is probably what I will be doing anyway as an outstanding recall has appeared on the mot gov website for my model and year.

Is it possible the smaller battery is the issue?

Any advice is much appreciated.

 

[Blobcat]

Hello and welcome

Firstly I’d take the battery back to Hellfrauds and order one of the correct AH

The glow plug light coming back on is indicating that one or more of the glow plugs has failed and /or the glow plug relay/controller.

 

[JBH1488]

Hello and welcome

Firstly I’d take the battery back to Hellfrauds and order one of the correct AH

The glow plug light coming back on is indicating that one or more of the glow plugs has failed and /or the glow plug relay/controller.

Thank you for the reply.

When my car went in for its MOT and full service on Friday they switched out the glow plugs and the glow plug relay and it didn't correct the issue so the garage have said that it isn't the module/relay or the glow plugs themselves causing the issue. I'll pop back to Halfords and I'll be making sure they stick in a 115AGM.

 

[Blobcat]

Thank you for the reply.

When my car went in for its MOT and full service on Friday they switched out the glow plugs and the glow plug relay and it didn't correct the issue so the garage have said that it isn't the module/relay or the glow plugs themselves causing the issue. I'll pop back to Halfords and I'll be making sure they stick in a 115AGM.

Is your garage a Mercedes specialist? I ask as we find on this forum (regularly) that many general garages struggle (at the owners expense) to rectify issues that a Mercedes “Indie” has probably seen hundreds of times previously.

Where are you based as we might have a decent indie nearby

 

[KennyN]

they switched out the glow plugs and the glow plug relay and it didn't correct the issue

Swapped with known good parts or replaced the components with new items ?

It is normally the relay or plugs , as mentioned , that causes the light coming on once the car is started as there is not much else in the circuit.

K

 

[JBH1488]

Is your garage a Mercedes specialist? I ask as we find on this forum (regularly) that many general garages struggle (at the owners expense) to rectify issues that a Mercedes “Indie” has probably seen hundreds of times previously.

Where are you based as we might have a decent indie nearby

Hi,

The garage I went to isn’t a Mercedes specialist. I initially took it in for the MOT and servicing and asked if they could take a look and they tried a new glow plug relay and new glow plugs and it didn’t rectify the issue(I think they didn’t clear the code after fitting them tbh to see if the problem would arise again).

They ordered the parts in, tried them and put my other parts back in. They were honest enough and didn’t charge me anything other than the mot and servicing.

I’m based in South Shields(Tyne & Wear).

Thanks.

 

[JBH1488]

Swapped with known good parts or replaced the components with new items ?

It is normally the relay or plugs , as mentioned , that causes the light coming on once the car is started as there is not much else in the circuit.

K

Not too sure Kenny. I think they get most of their parts in through euro car parts.

 

[rf065]

My old CLK had the glow plug light on for ages, to be honest it still started first time in the coldest winter so didn't worry too much about it. Replaced a glow plug and it went off for a while, then replaced the relay with a used one, which put the light off for a few weeks. It always came back on eventually so ended up ignoring it altogether, car always ran fine.

 

[mioba]

To be fair, a code reader would have identified which specific plug failed and they can also be simply tested, so replacing them all and the relay is overkill - especially to be told thats not the problem - is somewhat amiss.

I had the light on my W220 a few years back. I left it for my indy as I didnt want to attempt it / snapping a GP. He told me which exact plug failed. I asked him to replace all.

Did your garage scan for error codes.

 

[EmilysDad]

To be fair, a code reader would have identified which specific plug failed and they can also be simply tested, so replacing them all and the relay is overkill - especially to be told thats not the problem - is somewhat amiss.

....

When I had my R Class it went to a local Indie for something (really can't now remember what) and they said their diagnostics (no idea what) had said plug no 5 was goosed, however he then said that sometimes it could be the relay that's fubar'd. I replaced n5 plug & still got the gp warning ....in hindsight I maybe I should have tested the plugs rather take his word for it. Replacing the relay sorted it

 

[JBH1488]

My old CLK had the glow plug light on for ages, to be honest it still started first time in the coldest winter so didn't worry too much about it. Replaced a glow plug and it went off for a while, then replaced the relay with a used one, which put the light off for a few weeks. It always came back on eventually so ended up ignoring it altogether, car always ran fine.

The MPG hasn’t changed, the car starts perfectly fine and I haven’t really felt any dip in performance.

There’s a German prestige garage near me I might pop in there.

 

[onefortheroad]

Try a Renault Indy.

 

[JBH1488]

I’ve noticed today that if I clear the glow plugs code it goes off but comes straight back on when it’s the first start of the day.

If I let the engine get warm after driving then clear the code it doesn’t come back on.

But this morning the engine management light appeared as well.

 

[ajlsl600]

Good afternoon everyone,

So a few weeks ago by battery decided it had had enough and packed in. The RAC came out, he checked the car over, diagnosed the battery was infact dying and was only operating at about 1/4 of what it should be. So he jumped started the car and asked me if the glow plugs dash light was on before and I told him it wasn't, so he removed the fault code for it anyway. He tried selling me one of their batteries at £255 a pop, to which I kindly refused and told him I'd just pop to Halfords. He gave me advice, told me that it will be the 115AGM that I will need.

So off I went. Halfords only had 096AGM and the guy assured me that this battery would be absolutely fine. So the battery got fitted, I drove off and the next morning the glow plugs light was back on.

By this point the car was already booked in for its MOT and full service. They tried replacing the glow plugs relay and the glow plugs and this didn't fix the issue, which they were honest enough about and didn't charge me for the parts they'd ordered in and tried on the car.

Does anyone have any idea what the possible cause could be? The garage themselves didn't see too sure and just recommended taking it to Mercedes which is probably what I will be doing anyway as an outstanding recall has appeared on the mot gov website for my model and year.

Is it possible the smaller battery is the issue?

Any advice is much appreciated.

Not bad if they no charge u for parts not solving prob. But get correct batt. I doubt that will solve issue. But many mb electrical dramas resolved by batt change n wrong one won't help. On consumer batt get it checked if out of limits change it. They ain't a fortune.
If not Barr plugs or relay its wiring or some bug in control unit. Get codes read.
U fortunatly modern car electrics are often a blxxdy headache. That's just the way of it. Good luck.