Mercedes-Benz C180 - Starting Probelms - alan860


I am having a bit of starting trouble with my C180. Basically everything was going fine then one day it was problematic starting when hot.

Generally it starts first time in the morning, and once its running it goes fine. If I stop the car and start it straight away it starts first time. If however I stop it, wait 5 mins or so and try to start it the car doesn’t start until the second time (sometimes third) I try to start it (with the automatic cranking time given when you turn the car).

This all started in hot weather, and did once refuse to start when the weather was really warm (well warm for the UK anyway).

I have checked for fault codes and there is none. I have replaced the crank position sensor without any change. I have checked the coolant temp sensor (using OBD) and this varies nicely as expected.

Suggestions I have had include a lazy fuel pump, blocked fuel filter, and a faulty Cam position sensor.

The fuel filter was replaced about a year ago so is not due replacement, but can obviously get blocked anytime. I am however tending away from a fuel pump or filter as I believe that with an engine that has just been switched off (5-30 mins ago) the pressure should still be relatively high, definitely higher than after the car has sat all night. Therefore if there was a fuel issue I believe the car would be more difficult to start first thing in the morning (unless it was too high a fuel pressure).

Too high a fuel pressure should not cause starting issues unless the engine is being flooded which im pretty sure it isn’t. The Long Term Fuel Trim was around -2%, so although running a bit rich I think there is not too much of a problem there.

Another, most probably unrelated issue is that the fuel system only goes into ‘Closed Loop – Fault’ and reports that it may be running on one lambda sensor. However the pre cat sensor is fluctuating nicely and the post cat sensor is around a constant 0.7V so both look ok.

Short of replacing all the fuel system I am starting to be at a loss what may be the problem here, and don’t particularly want to replace components on spec so any advice someone can give would be most welcome.

Thanks in advance,


Mercedes-Benz C180 - Starting Probelms - Avant

Moved to Technical. It would be helpful if you confirm that this is a petrol - I don't think there was a C180D but wouldn't swear to it.

Mercedes-Benz C180 - Starting Probelms - elekie&a/c doctor

Bit more info would help.Is this a 202 or 203 chassis series and what year?If it is a 203,then there are 2 engine types for a 1.8.Also if you are using a generic obd reader then this may not give enough info on the engine control system.hth

Mercedes-Benz C180 - Starting Probelms - alan860


Thanks for moving the question, and the answers so far. The car is a 2.0l Petrol engine with a w203 body.



Mercedes-Benz C180 - Starting Probelms - elekie&a/c doctor

I would be inclined to replace the fuel filter as this incorporates the fuel pressure regulator.Try and use an original part or a top make (bosch ,Mann etc)as I have seen fuel delivery problems on poor quality filters.hth

Mercedes-Benz C180 - Starting Probelms - alan860

Thanks for the advice, fuel filter was next on the list but I had thought it unlikely due to being difficult while hot. Wasn't aware that the pressure regulator is in there too, so it makes more sense now.


Mercedes-Benz C180 - Starting Probelms - djadju

I have identical problem C180 2.0 95kw (203.035). Last summer I had to change the fuel pump.

Now this summer the same problem.I replaced the sensor position the shaft and the fuel filter.

I do not know what to do. How have you resolved the issues?

Mercedes-Benz C180 - Starting Probelms - injection doc

get the engine hot. Leave the injectors connected but pull them out the cylinderhead and place each injector tip on a brown envelope and leave overnight.

If there are fuel staines on the brown envelopes the injectors are leaking and flodding the engine with fuel making hot starting very difficult


Ask Honest John

Value my car