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Hello, got my first mb yesterday (c180 Coupe 2012) and having issues
Hi there, my first post.
I picked up my first Mercedes yesterday, about 30 mins in to the 100 mile drive home a warning on the dash said Coolant Stop, Engine Off.
The temp gague was at max 120 and it was in limp mode.
I stopped at the next services for 20 mins, started up and it was fine for the whole journey home, which included a couple of stop offs.
Today, I've had 3 instances of the car jerking when accelerating and then going into limp mode. No dash warnings, but again the temp gague is on max 120.
If I turn the ignition off and start up again it goes back to normal.
Are you losing coolant, can you see it dripping from under the car? Can you see any active leaks under the hood from a hose or coolant dripping down the engine?
Do you notice the fan in the engine bay running? With the gauge showing the car over temp the fan should be running and pretty loud.
With the engine cold start it up and watch the temp gauge, when it gets to around 90-100 it should stop and maybe even slightly go down. Thermostat should open at this point. Or does the temp just keep rising?
Erratic temperature gauge is not very common but does happen with the M271. Scan or have it scanned for codes as recommended by @JettaRed but you may find none relevant to the problem. If so, it could be a bad temp sensor, a bad wiring connection at the unit, or a grounding problem. Keep us posted and we’ll try to help.
I've got it booked in for diagnostics on Tuesday, so I'll post an update then.
Doesn't seem to be any leaks and it's just random. The temp just seems to jump straight to max and when restarted it goes straight back to normal range and stays there untill the next time.
I've tried running the air con on max for 15 mins this morning with the cap off and went for a drive and the temp never spike and there was no juddering, then went to the garage and he said best not to drive it until he has looked at it, just in case. He said hopefully it's just a sensor, but could be a number of things.
I plugged in a cheap obd reader my brother had and it brought up the below, I'll see what the garage says when they run the diagnostics on Tuesday. But they seem to relate to the issues.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Generic OBD readers are WORTHLESS when it comes to Mercedes. Get a proper Mercedes scanner. Look for Launch Creader Elite 2.0 BENZ on Amazon and order it today.
P0339 indicates a failed CRANK sensor. Usually, your car will not run at all with this code.
@Sharpy24 - hey, sorry to hear about your car troubles...
Definitely do not drive the vehicle with over heating conditions you can start to melt internal components..
AS previously suggested you can do many visual checks to see if there are any 'smoking guns'.
Was the car ever in a flood or an accident?
"Usually" when the temp gauge fluctuates up and down you have a bad thermostat. The c250's are known for having that issue. There is also a coolant check valve and auxiliary coolant heater some c250's came equipped with. Did yours come with that? It would be clipped into the white plastic clip on the coolant over flow bottle.
Thanks for the reply, there is no auxiliary coolant heater there.
I've ordered a Launch Creader Elite 2.0, so I can look things up myself.
It's been in for diagnostics today, they cleared all the codes, ran it for a while and said everything was running as it should, and the thermostat was operating correctly, so they said to run it for a bit and look for any codes coming back, the dealer refunded the costs straight away to be fair to them.
I won't pretend to know what most of this means, but i'll start to look into things and learn.
That translates as:
-- Crankshaft sensor is going to limp mode
-- "bus awake" means hyper active battery drain
-- or average disruption from CAN-C gone wild
Last edited by CaliBenzDriver; Aug 21, 2024 at 04:59 PM.
So after the codes were cleared the other day, the temprature has been fine, but the jerking and into limp mode started again last night under slow acceleration, no warnings on the dash.
It's booked in with a Mercedes specialist on Tuesday to have the crankshaft sensor replaced, so fingers crossed that might sort it. If not it's under 30 days, so I'll hand it back and look for another one, the problems haven't put me off getting another one as I love it.
The launch reader is due tomorrow, so I'll see what that brings up.
using your new scanner, you can easily drill down into the crankshaft sensor fault to see what else can be involved... like coolant leaking onto sensor connector sort of things.
While booking your car at the front desk, request to have camshaft position sensors checked for oil contamination.
Last edited by CaliBenzDriver; Aug 24, 2024 at 03:52 PM.
The crankshaft sensor was changed yesterday, and so far so good. It's running as normal after a few trips out and no code has come back. The mechanic says it looks fine and just needed the old one replaced.
I'll take it out at the weekend for a proper run, and keep my fingers crossed.
Seems mad that a little £35 sensor could cause all of that.
Now just the drivers door speaker not working, but I can live with that for now.
When the diagnostics was done they said the thermostat was working as it should, so hopefully that was due it it sitting around for 6 monthes or so before I got it, the code for that hasn't come back as if yet.
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