Andystyle

Hey guys, don't know what's wrong was out in the city last night, left the car with a valet got it back during the ride back. ENGINE LIGHT poped on
And eng Temp was reading above 80 which is middle marker but not all the way up about 5 white markers above 80!
Called merc but not appointment till Tuesday, so am scared to drive the car, what do you think i should do...btw car's an 09 not even 7k on it yet!

VinniE_C4_MatiC

I would at least ask the valet management to see any cameras they have watching the lot to make sure nobody was foolin with ur car. Give them date and time and ask to see the tape if u can. Don't let them know right away ur check engine light is on just tell them u think somebody might have been in ur car when they shouldn't have been. I wouldn't drive the car around unless I definitely had to until u bring it in.

Good luck

AMGTTV8

I wouldnt worry....our cars run 85-90 degrees celsius...

I say it's some sort of minor mechanical issue such as faulty sensors etc...

if something major was wrong you would know

whiteongrey

Try and reboot the ECU via the pedal to the floor and key in 2nd position - or something like that (it's described in the forum somewhere)...or whatever...see if it returns.

AMGTTV8

That will do absolutely nothing - once the code is stored in the computer, it is there until the tech hooks up the computer and clears it out.

furthermore, the process referenced above only resets the driver-adaptive throttle and transmission to baseline settings.

Carsy

Most practical people would check their coolant & oil when an engine light came on.

Onizuka

The CEL light might come on if they mess around with your gas tank.

Andystyle

Well the valet wasn't like a take your car and put it in a garage, he had it parked right infront of the resturant, Second the car has recently been to Merc about 3 weeks ago for an early oil change and all fluid tap off.Am hoping it's a faulty sensor, i just took it for a ride, everything runs normally even the temp gauge is back to around normal 80deg (middle). But the light's still on, Am going to try not to use it much and wait for Merc to take it Tuesday.

joshg1001

could be a number of things. loose gas cap, O2 sensor...its a waiting game now

JimPap

When my "check engine" light came on, I took it to the dealer to see if it was something serious. The first thing he did was unscrew the gas cap, then put it back on. That didn't clear the light, but thought it might.

They were a little slow that day and was able to go ahead and take the car in for service. Turned out to be some kind of cam magnets. It was covered by warranty.

jstaneff

When mine came on, I stopped the car, got out the manual, and read up on the light. It's not about coolant or oil, but it does mention either gas or emissions. It also says "drive to the nearest MB dealership for service."

Mine was an Exhaust Cam sensor problem, fixed under warranty.

acr2001

If your coolant or oil was low you would get a specific message about that, NOT a check engine light. If a very serious problem is detected you would get a red display and possibly a message to pull over and turn the engine off (depending on the problem).

The light can come on if your gas cap wasn't installed tightly enough (the W203 manual says that the low fuel light would also be flashing in that situation to make it more obvious, not sure if that's been changed).

Glyn M Ruck

All modern car owners should carry a cheap $50 OBDII/CANBUS scanner in the glove box. Then you can read codes and will know why the car threw a CEL.

Likely something minor or the car will go into limp mode & give you warnings.

If it is not overheating & is not low on fluids then just drive it. The thermostat on these cars opens at 87 Deg Celsius so that's approx normal temp.

axhoaxho

It is actually a good idea.

Can anyone suggest a good model of OBDII/CANBUS scanner for our car?

Thanks,

Andystyle

Well gas cap was on tight, even had to put gas in today. So made sure, but seems when these warning ligths go on only dealer can take it off, cause it's still on. Anyway got an earlier appt for this afternoon for a drop off, will keep everyone posted when i get it back tom morning on the cause. Thanks all for keeping me cool!

Ron Jr

My CEL light came around Christmas took it to the dealer and they replaced two O2 sensors.

JimPap

Good idea.

It'd be nice to know about some of the minor stuff that doesn't cause a light to go off.

joshg1001

where do you even connect the scanner?

f8al

I haven't verified this in my c300 yet, but under the dash on the driver's side is the first place I would look. It might also have a plastic covering.

C300Sport

I have heard the W204s go through O2 sensors like a fat kid through doughnuts...have they fixed the issues with the new sensors?

Andystyle

Okay everyone, took the car in yesterday to sort out that engine light problem...Well after an Hour in Merc got it back nothing serious, but he did say it was caused by the gas cap being loose, Hey i didnt mind as long as they did a full sweep of the car okay...But in this merc service area there's an observation deck where owners can go there's a big two way glass mirror that over looks the entire garage where the cars are...Now i've been keeping on eye on mine, and during that hour there were total of 5 guys at once! looking at my car and the computer read outs, now that scared me a little, if it was just a loose gas cap, do you really need 5 guys to figure that out? I don't know maybe it's just me, but do you think there not telling me something?

JimPap

Andy,

Yeah, that doesn't sound right to me either.

I know the first thing my service writer did was check the gas cap and only wrote it up for service when that didn't work. Maybe it was the reverse for them. They didn't check the easiest and most obvious.

In case they just disabled the "check engine" light, you might want to loosen the gas cap and see if the light comes on.

joshg1001

lol if the light comes back on, hes going to have to get his own scanner or go back to merc (or some auto repair shop)

JimPap

Tightening the cap won't cancel the light?

acr2001

Sure it will. You have to keep in mind the type of scummy liars you are dealing with when you take your car into the dealership. They are NEVER to be trusted!