Glow plug warning light W204 C220CDI

[markg14]

Had a glow plug warning light on for the last month, and requested new glow plug from my local indie.

The cheeky gits tried to charge me £60 for "diagnostics", despite me telling them, and the dashboard warning light being on when starting first thing in the morning.

Glow plug replaced, but very next morning the warning light has returned.

Garage are now saying that they think it might be something else - like a relay.

Anyone else had this problem?

I can't believe they wanted to charge me £60 for diagnosing the problem, and then saying they mis-diagnosed it!

 

[EmilysDad]

If all glow plugs have been changed, then it's very likely it's the glow plug relay.

I'm sure someone will able advice where it is on your car

 

[markg14]

If all glow plugs have been changed, then it's very likely it's the glow plug relay.

I'm sure someone will able advice where it is on your car

No, just the glow plug number 4, as indicated on the MB fault log

 

[EmilysDad]

No, just the glow plug number 4, as indicated on the MB fault log

If one of them has failed, chances are the others wont be far behind. Without looking, I don't know how much a relay is for your car (a V6's is around £140) but even at MBs prices, 3 glow plugs is likely to be cheaper than the relay.

I'd change or get changed the remaining 3 plugs & go from there. STAR told me that no 5 plug was goosed, but it turned out it was the relay. Glow plugs are straight forward to change yourself, providing they don't shear ..... which they have a habit of doing so. The relay on mine ... assume yours is similar .... took longer to find than it did to change.

 

[markg14]

Don't understand the logic of your answer.
Change 3 glow plugs because they are cheaper than a relay??
I just want the faulty component (a) Identified and (b) replaced.
Despite replacing number 4 glow plug, diagnostics are still saying fault with number 4 glow plug.
Charged £38 plus VAT (£45) for glow plug.
Also, I believe there is a fusable link in the relay that can easily be repaired.
Anyone know anything about this please??

 

[EmilysDad]

Don't understand the logic of your answer.
Change 3 glow plugs because they are cheaper than a relay??
I just want the faulty component (a) Identified and (b) replaced.
Despite replacing number 4 glow plug, diagnostics are still saying fault with number 4 glow plug.
Charged £38 plus VAT (£45) for glow plug.
Also, I believe there is a fusable link in the relay that can easily be repaired.
Anyone know anything about this please??

Change the relay ...... but as said, you've got another 3 glow plugs ready to fail. You don't need an indie or MB to do either .... do them yourself

 

[Lord_Lucan]

It can be nerve racking to do them yourself but I changed mine in my 4 pot engine. I soaked them with plus gas then ran the engine to heat it up, then another liberal spray, then a quick 5 minutes blast up the dual carriageway and another spray when parked up at home.

Using a torque wrench set to undo at 15nm I gave one a go and it undid without any issues. Did the remaining 3 like this too and thankfully none snapped.

Total cost £32 from euro car parts for beru plugs x 4. Beru are oem plugs too.

 

[KennyN]

Plugs can be checked with a MultiMeter , no need to run an expensive STAR check.

A STAR check will , however, show up a duff relay.

You say you asked them to fit a new GP , which one as there will be four ?

The light normally signifies one or more duff plugs.

Kenny

 

[Wighty]

There isn't a fusible link in the relay that can be easily repaired . Maybe check the electrical connection on top of GP number 4 if it is still showing a fault . I must admit I only change glow plugs when they are faulty now , rather than all 6 just because 1 is faulty .
As said above a cheap multimeter will show which GP is faulty , and if they all test ok on the multimeter then it probably is the relay that needs doing . My relay was replaced because the car was becoming harder to start earlier this summer , the GP light never came up on the dash .

 

[EmilysDad]

.... .

A STAR check will , however, show up a duff relay.

No it can't. When my relay was fubar'd, STAR said it No 5 glow plug was u/s

 

[Lord_Lucan]

When I checked mine with a meter none gave open circuit readings. A couple gave odd readings, I can't remember if they were very high or low but they were out of Kielter with the other two.

Unless I'm mistake the OPs car will be a 4 plug engine so worth metering them but as others have said if one or two have failed them the others can't have too long left.

If it helps reassure you I did mine when the car was 12 years old with 98k miles done on the original plugs so they might not snap you know.

Link to a thread I started in case you wanted to have a read: by no means is it a DIY article though: http://forums.mercedesclub.org.uk/index.php?threads/w203-glow-plug-light-on-dash.157688/

 

[KennyN]

No it can't. When my relay was fubar'd, STAR said it No 5 glow plug was u/s

Yes it can , when i had mine "STAR`d" it gave whichever fault code it was for a duff relay , i have the printout somewhere and i think it states GP control module open circuit . The GP`s were fine for a few months after the relay was replaced then one of them gave up the ghost so i replaced all of them whilst i had the weapons out.

Kenny

 

[EmilysDad]

Yes it can , when i had mine "STAR`d" it gave whichever fault code it was for a duff relay , i have the printout somewhere and i think it states GP control module open circuit . The GP`s were fine for a few months after the relay was replaced then one of them gave up the ghost so i replaced all of them whilst i had the weapons out.

Kenny

Not in my case ..... the halo'd STAR said it was No5 glow plug ..... it wasn't

 

[houseboss2]

Glad I have not got a diesel

 

[Mr Filipov]

Glad I have not got a diesel

You're right. An 8 cylinder engine with 2 spark plugs per cylinder is so much better hahaha