W204 C180K engine diagnostic light on

Page may contain affiliate links. Please see terms for details.

190

MB Enthusiast
Joined
Mar 4, 2015
Messages
5,305
Location
Cheshire
Car
2009 W204 C180K
The yellow engine warning light came on today approx. 1/2 mile after a cold start. The car drove perfectly for the next 10 miles but the light remains on.

I've been meaning to buy a scanner anyway but I read somewhere that if it was fleeting fault the light will clear itself after 3 re-starts. Can anyone comment on that.

I'll do a search first before I ask what scanner to buy.
 
Depending on what triggered the warning light (and assuming the fault is not still active) the light may extinguish after a number re-starts but surely it is better to know what the fault light is indicating?

As for a scanner, you may buy a simple Bluetooth OBD scanner for under £5 and use an app such as Torque or buy much more complex scanners for £100 or so.
 
I've searched the forum and I think I'm going to go for a ELM 327 blue tooth OBD scanner. I've got as far as realising that "ELM 327" is only a generic title. ELM 327 is actually the name of the chip that these devices contain. As they are so cheap I need to figure out if it's worth buying a genuine device from a reputable source.
 
The ELM327 devices, together with the cheaper code readers, will only read the emissions related codes as that is what OBD2 was originally designed for. Vehicle manufacturers spotted the opportunity to add their own diagnostic information using proprietary data streams, to cover things like transmission, heating ventilation and air conditioning, active suspension and so on. This data is usually unique to individual makers and you'll need to spend a good bit more for a manufacturer specific reader.
 
The yellow engine warning light came on today approx. 1/2 mile after a cold start. The car drove perfectly for the next 10 miles but the light remains on.

I've been meaning to buy a scanner anyway but I read somewhere that if it was fleeting fault the light will clear itself after 3 re-starts. Can anyone comment on that.

I'll do a search first before I ask what scanner to buy.

It might be worthwhile checking the running temperature; it should be in the 90s. My 180 triggered the EML due to a faulty thermostat. Apparently this is flagged up because a low engine temperature affects the emissions...at least that was what I was told by my Service Advisor. He was able to tell me accurately from STAR what my actual temperature was; from memory, it was in the high 70s.

Ernie
 
I would plug the car to Star Diagnosis :-D just to make sure it is not rout timing chain
 
Well I'm hoping it's not the timing chain at 57,000 but I will go easy on the revs until I find out what the code is. The light came on at 2000 RPM so it wasn't being driven hard.
 
I would guess its the air pipe that sits below the air filter box, very common on that engine, mine came on and had no effect on driving.
I think a new pipe is about £15, maybe £80 fitted, bit awkward to get to.

Here's a similar problem - https://www.mbclub.co.uk/forums/engine/143102-engine-management-light.html
 
Last edited:
The ELM327 devices, together with the cheaper code readers, will only read the emissions related codes as that is what OBD2 was originally designed for. Vehicle manufacturers spotted the opportunity to add their own diagnostic information using proprietary data streams, to cover things like transmission, heating ventilation and air conditioning, active suspension and so on. This data is usually unique to individual makers and you'll need to spend a good bit more for a manufacturer specific reader.

Sorry...but that is not true.

My ELM327 along with the Torque App on my mobile read error codes for my 7g transmission and told me the number BUT it does give the wrong information what the error code is....the number is correct but you have to look that number up on the MB site to get the true problem.

The error codes explain mainly for petrol so of course the diesel engine although the same code a different problem to what is wrong.

The error code number is always correct.
 
I have a scanner on order but in the mean time it might be worth looking at this air pipe under the air box. Now you mention it I remember reading about it. If it's only an hours labour it can't be that hard to get to.
 
Well the light went off this morning on the 3rd cold start. I guess the code will have been stored so it will be interesting to see what it was when the scanner arrives.

I learnt something along the way that might be of use to others. It's obvious you can't work on a modern MB without male Torx bits and and female Torx sockets so you need to buy a set. To remove the air box you need an E10 female Torx socket. However 99% of Torx socket sets come with the E10 socket that is 3/8 drive and it won't fit because MB restricted the access with a silly plastic guide tube. You must have a 1/4 drive E10 which is not so easy to find. It's probably better to buy individual sockets as 3 sizes - E8 , E10 and E12 seems to cover most things.
 
When the scanner arrived there was only one rather non specific code stored P0100 - Mass Air Flow. That was over a week ago now and the code hasn't come back.

The very cheap ELM327 bluetooth scanner with Torque App worked fine with an android phone. I'd have left it connected to the OBD port but there must be some small current draw as the thing lights up even with the ignition off.
 

Users who are viewing this thread

Back
Top Bottom