W203 C180 Engine Management Light

[Fidget]

I've had the engine management light come on on my w203 C180K a couple of times and strangely topping up the fuel tank has cleared the light.

The first time was around a month ago, I was sat in traffic and the light came on. I looked it up and saw that the possible causes were either an almost empty fuel tank or a fuel system fault. The car was running fine but I had recently filled up with super unleaded as regular (which I normally run on) wasn't available. I still had 1/2 a tank of super but thought it could be the fuel, so I went to the garage, filled up on regular, turned the key and the management light immediately went out.

Around 700 miles later, I was sat in traffic tonight and the engine management light came on again. This time I had 3/4 tank of regular unleaded and the car was running fine once again. It was serviced and MOT last weekend, passed emissions test. I cannot see anything obvious wrong. Perplexed I thought I'd try refuelling again. Put £20 of unleaded in which filled to the brim. Started the car, light went out immediately!

This would ordinarily indicate to me that there might be a fault with the sender unit in the fuel tank possibly telling the ECU it's near empty, however the fuel gauge is working? The fact it happened in traffic also made me think a sensor (MAF/ Lambda?) but no issues on emissions test last week and how would refuelling clear the fault if it were a sensor? The car runs like a dream.

Having just spent £600 on suspension repairs I'm reluctant to go in for a diagnostic on the off chance. The light remains out for now, but it's bugging me.

Has anyone had similar issues? Any ideas? Grateful for any advice !

 

[Fidget]

Further to my last, I should add that I have also checked that there is no oil in my cam shaft sensor wiring plugs which I understand can be a common cause of engine management issues....

 

[television]

What is the mileage of the car please

 

[Fidget]

It's 57,000 miles, 2005 year M271

 

[Fidget]

A quick update on this fault.

The engine management light comes on only when the car is stationary, engine running and the gearbox in Drive after approx one minute.

It doesn't trigger when in the engine is running but gearbox in Park.

I'm thinking emissions? Any ideas?

I can reset the management light rather unusually by topping the fuel tank up to full (it just goes out when I refuel).

Grateful for any advice or help.

Ps. is there a way to reset the management light manually?

 

[Jdokal]

I reckon it's the chain stretching...I could be wrong....the M271 is a well documented engine regarding the chain jumping from (but not solely) worn camshaft sprockets.

 

[Fidget]

I hope it is not the chain. The car is running absolutely fine and I have no symptoms at all, other than the warning light comes on whilst sat in traffic. I have noticed on first start up it does occasionally smell like it's running rich though.

 

[daveenty]

Get the fault codes read by someone with a proper set up (STAR ideally)

That way you're not second guessing at it.

 

[Fidget]

Okay, so I booked the car in with the main dealer and have an appointment tomorrow. On Friday night I also put a bottle of Wynns petrol system cleaner in, on the off chance.
Light stayed on all weekend, probably did 20 miles at most.
This morning started car, and the engine light has gone out. Sitting in traffic did not bring it back on as usual. How strange, maybe the fuel cleaner shifted something ?

If I take it to the dealer for a diagnostic (£110) as planned tomorrow, will they be able to get any codes from it now that the light is off?

 

[television]

Yes the code will be stored,,,, what a shocking price to just plug into STAR for a few mins

 

[Fidget]

Thanks for the quick response. I will probably go ahead and get it plugged in just in case it's something serious. I thought the price was very expensive though my mate was recently charged £100 by VW for the same. It's disgusting really for what is a ten min job !

 

[television]

An indie would charge £30 to £40 for this. I would not bother doing it if the car is running OK.

 

[Fidget]

That's quite a saving over £110. I've cancelled the main dealer and I'll see how it goes. If it happens again I'll see if I can find an Indy with diagnostic kit. Car is running fine currently.

 

[television]

You can have the codes read when in for a service, it does not take much to turn the lamp on sometimes, the fact that it has gone out is a good sign.

 

[Fidget]

An update on this - Fixed (I hope!).

The light came on and off several more times, and the car almost felt like it was going to stall on one occasion when the light came on.
I found an independent MB specialist who charged £30 for a diagnostic and identified (very quickly) that my issue was a split hose under the air box. Not the thin hose which is easy to see, but the larger hose which is lower down.
This was replaced for the cost of an hours labour plus the part. The total bill was less than the main dealer wanted to do a diagnostic alone.

I'm told that this pipe is a common problem.

Hopefully all sorted now :-D

 

[television]

That is good news.

Just some points on engine MIL lamp.

The lamp will turn on when the fault is present on 2 twice in succession.
The lamp will go out after 3 clear starting cycles.
You only need to stop the car to avoid CAT damage if the lamp is flashing.