I looked at the coolant tank and couldn't see the minimum mark so assumed it was already above the minimum, but because the light was on I put a little bit of coolant in and hoped that was the issue, after getting stuck in traffic again, the light come on.
W204 c63 coolant light come on in heavy traffic
- Thread starter Chris63
- Start date
Page may contain affiliate links. Please see terms for details.
As long as it has some coolant, the temp could hold steady with a small weep but the fans would have to kick in and work harder.
If no weep, than its likely the thermostat has lost its efficiency. A good thermostat will regulate well enough, and the fans will rarely or only kick in occasionally.
Touchwood, it's not a major problem, just a bit of inconvenience. The OP will be up and running again
If no weep, than its likely the thermostat has lost its efficiency. A good thermostat will regulate well enough, and the fans will rarely or only kick in occasionally.
Touchwood, it's not a major problem, just a bit of inconvenience. The OP will be up and running again
Yeah my hunch (literally only a hunch as I don't have a clue) says thermostat, honestly don't know, I'll leave that to the garage on Monday and give him the warranty company's number and hope I don't need to open my wallet!As long as it has some coolant, the temp could hold steady with a small weep but the fans would have to kick in and work harder.
If no weep, than its likely the thermostat has lost its efficiency. A good thermostat will regulate well enough, and the fans will rarely or only kick in occasionally.
Touchwood, it's not a major problem, just a bit of inconvenience. The OP will be up and running again
ALFAitalia
MB Enthusiast
- Joined
- Feb 19, 2022
- Messages
- 5,625
- Location
- Bognor Regis
- Car
- 2009 ALFA 159 2.0 JTDM, Merc A170 (W169), Merc CLK 200K (C209) gone, 1999 Merc SLK 230K (R170) gone.
Good news....too new for the head bolt issue. The only reason I mention it is that a friend of mine is fixing his one now.....two snapped head bolts......his is 2011....but only 38,000 miles.
Jesus that's scary isn't it, just out of curiosity, how much is the head bolt job? I heard this is the reason to stay away from earlier models but surely can't be that expensive?
- Joined
- Mar 11, 2013
- Messages
- 10,682
- Location
- South Bucks
- Car
- CLS63 SB, SLK55, CLK350 'Vert, Triumph Sprint (Bike not Dolly...),
Think about it.
The light came on; you could not see the minmum level marker when you topped it up, so it was not low on coolant when the light came on the first time
You topped it up, so it was not low on coolant when the light came on again.
The temperature gauge shows a steady and correct temperature at all times, so your thermostat is fine.
(If it's not, what are the chances of the temperature gauge playing up and wrongly indicating the correct coolant temperature at the same time? Vanishingly small, I'd say).
UNLESS you're having to keep topping it up, you're not low on coolant, so you don't have a leak.
It's the sensor that triggers the light and the fans that is causing the problem, I'd say.
The light came on; you could not see the minmum level marker when you topped it up, so it was not low on coolant when the light came on the first time
You topped it up, so it was not low on coolant when the light came on again.
The temperature gauge shows a steady and correct temperature at all times, so your thermostat is fine.
(If it's not, what are the chances of the temperature gauge playing up and wrongly indicating the correct coolant temperature at the same time? Vanishingly small, I'd say).
UNLESS you're having to keep topping it up, you're not low on coolant, so you don't have a leak.
It's the sensor that triggers the light and the fans that is causing the problem, I'd say.
Everything you say makes perfect sense. I hope your right. Hope the garage down the road is an honest one! Saves me driving 35 miles to my normal merc specialist, I'll let him diagnose then report back to you guys!
Unfortunately the coolant temp sensor cannot be changed, its built into the thermostat housing along with the plastic return feed from the expansion tank and the thermostat itself.
It's all one unit.
The part number is A1562030475 for the M156 engine.
It's all one unit.
The part number is A1562030475 for the M156 engine.
- Joined
- Mar 11, 2013
- Messages
- 10,682
- Location
- South Bucks
- Car
- CLS63 SB, SLK55, CLK350 'Vert, Triumph Sprint (Bike not Dolly...),
The coolant temp sensor appears to be functioning perfectly. I'd say the fault is with whatever sensor illuminates the light and switches on the fans.
On the plus side, thermostat is covered by warrantyUnfortunately the coolant temp sensor cannot be changed, its built into the thermostat housing along with the plastic return feed from the expansion tank and the thermostat itself.
It's all one unit.
The part number is A1562030475 for the M156 engine.
Mines done 119k. Last summer i changed the head bolts myself as a precautionary measure, they were the T55 bolts. I didn't see any significant corrosion, two bolts had some browning, light surface pitting but didn't look like they were about to give way.
T60 bolts were introduced around 2010 ish, and then the final E14 were the superceded ones. Those bolts are male version and have more material on top. The T55 and T60 are female type bolts, and have less material so I suppose can weaken if they corrode.
I do believe regular antifreeze change is important, it contains anti corrosion inhibitors which can help reduce any chances of corrosion.
I think the ecu controls the fan, low and high speed, there is usually 1 or 2 fan relays in the fuse box. On my Hemi, weirdly there is 2. Not sure on the arrangement on my w211 though but I think it should be the same as they were both Diamler Chrysler products during that era.
Continental
Active Member
- Joined
- Feb 25, 2009
- Messages
- 242
Amber light as in engine warning light or specific coolant notification of sorts? If there is anything up with the coolant surely check coolant or similar would pop up. Having said that, if you suspect something is up with the coolant’s abilities eg: it may have deteriorated over time, for peace of mind I would flush/replace it all out completely if it hasn’t been done in the last say 5 years - cheap enough then you’ll know the coolant should be up to the job as far as the liquid is concerned.
Skd884
MB Enthusiast
- Joined
- Sep 13, 2017
- Messages
- 3,534
- Car
- c180 w204
Coolant change is due at 115k/15 years 204 c63.
ALFAitalia
MB Enthusiast
- Joined
- Feb 19, 2022
- Messages
- 5,625
- Location
- Bognor Regis
- Car
- 2009 ALFA 159 2.0 JTDM, Merc A170 (W169), Merc CLK 200K (C209) gone, 1999 Merc SLK 230K (R170) gone.
He is doing it himself with my help. Doing a few other jobs while it's apart like cam plates and injectors and fitting upgraded followers to avoid the other potential issue with these lumps....so should be good for a while when she's zipped back up.....so no idea how much a dealer/Indy would charge....quite a bit I guess. The head bolt issue does not seem to be so much of an issue here....over on MBWorld (USA) it seems much more common. Constantly dropping coolant levels being the first clue. Many owners do the bolts as a precautionary measure....some doing them one bolt at a time and not replacing the gaskets. On that forum it seems like anyone buying an M156 engined car with old style bolts factors the cost of a potential bolt/head gasket job into the price. Seems a bit OTT to me....but there are a lot of M156 bolt failure threads on that forum.
It's literally just the Amber light on the picture in the original post, no "bings" or anything when it comes on, just comes up then fan comes on then when I get out onto open roads at 40mph+ the light goes out and the fan goes off.
I took it to my local garage this morning and the error message on the diagnostic machine just said "coolant error " and that it... the garage couldn't get it up on the ramp cus it was to low so that's as far as they went with it. The said they suspect it could be as little as a sensor and could be as much as a head gasket.. gee thanks that's helped alot...
Booked into d&b mercedes specialist in bristol on Wednesday. Just means I can't enjoy her this weekend in the sunshine!
Hi guys just an update!
D&B automotive, Mercedes-Benz specialist in Bristol... amazing garage by the way!
They diagnosed it as a faulty module that controls the fan, therefore replaced the fan and the module, dealt with my warranty company for me and got payment off them (thank god, it expires 9th of next month) the module was working at less than 10% of what it should have been... picking it up tomorrow evening.. fingers crossed all good!
D&B automotive, Mercedes-Benz specialist in Bristol... amazing garage by the way!
They diagnosed it as a faulty module that controls the fan, therefore replaced the fan and the module, dealt with my warranty company for me and got payment off them (thank god, it expires 9th of next month) the module was working at less than 10% of what it should have been... picking it up tomorrow evening.. fingers crossed all good!
