2014 E-Class Convertible (A207) E 220 CDI Suspected Fuel Issue

[settloe_99]

Hello,

I'm hoping for some advice on my car, which was stuck in limp mode one morning and has been at a local garage for about six weeks.

So on going out in the car one morning, it immediately went into limp mode when I accelerated off the drive. I turned around, parked it up and had it recovered to a local garage that I've used before. They initially plugged it into their diagnostic system and said they couldn't identify the issue, but they used another local garage with more advanced diagnostic systems. The car was moved there, and this garage said that their diagnostic system was showing an issue with the fuel system, but that was as specific as the system tells them and contrary to what people think, these systems don't specifically tell them which part is causing the fault (and even Mercedes can't find out the exact part that is causing the fault), but they suspected the fuel pump was faulty.

The second garage was too busy to replace the fuel pump, so the original garage went and picked it up, and it drove back to their garage perfectly fine without going into limp mode. This made them suspect it wasn't a faulty fuel pump, as they said it would either work or wouldn't. Since then, they've changed a sensor on the fuel pump and two sensors in the fuel rail, and the car is still in limp mode. The fuel pump was then taken off and sent away and tested, and they said it wasn't delivering enough fuel, so it was stripped down and repaired. This hasn't worked. The garage is saying they suspect the fuel system has had petrol in it at some point in its life before I bought it (April 2022), which is why all these issues are occurring.

My partner has used the garage for years and trusts them, but what I'm trying to get to the bottom of is whether this garage is just out of their depths and if the car went to Mercedes or an independent Mercedes specialist would they be able to diagnose the exact cause of the issue more accurately?

Thanks for any help!

 

[malcolm E53 AMG]

Yes, take it to a good Independent who specialises in the marque I’m sure with their inherent knowledge of MB and use of STAR diagnostics they’ll soon solve the problem it could be injector related by your description but that’s just a guess

 

[settloe_99]

Thanks

My gut feeling is that the local garage doesn't have the proper diagnostics and is just guessing what the problem could be!

 

[supernoodle]

Take it somewhere else. If the garage really did see anything on the diagnostics it might have been something like a P0087 Fuel Rail/System Pressure Too Low. I can imagine that someone who doesn't know what they are doing would start replacing parts. There is no reason to though, there are plenty of tests that can be performed to diagnose.

If there were no codes, still no reason. Test, test, test until you're sure.

 

[harrye500]

As others have said, find a good indy. Most local garages although probably fine in the most part won't spend the money they have to pay MB to use their technology or jump through the doubtless hoops MB likely insist on! MB indys pay 1000's to use MB systems but they know what they're talking about

 

[Steve@Avantgarde]

Awful set of circumstances here.

Firstly, fuel pressure wont cause any limp mode faults, itll just cut out or not start. Basic knowledge of diesels for the garages should be a help here.

Secondly, diagnostics and advanced diagnostics, well, there is no such thing. Diagnostics can be done with the most basic scanner providing you have a good working knowledge of electrics and component operation combined with a skillset with a multimeter.

Thirdly. Use an independent specialist who knows what they are doing. Perhaps you could state your location so perhaps we can recommend someone.

 

[pgh13]

Could it be transmission induced? What's the milage, etc. of vehicle and is there any record of transmission being serviced?

 

[Steve@Avantgarde]

With a proper scan at an Indy we wont know anymore than we do now and anything will just be plain guess work and there is no point guessing any more.

 

[mioba]

A good merc indy is worth its weight in gold. They are familiar with the marque and the associated quirks.

AN other garage as in your case are searching blind and clearly guessing (at your expense) till something sticks. A reputable garage not doing the work because they are busy - tells you something about thier ability - why take it in then?
If its been working for months before the point in miscue ling is BS.

Whats your location. Someone may be local and know of a reputable indy.

 

[Uncle Benz]

When was the fuel filter last changed?

Like Steve says, it’s complete guesswork with what information you’ve shared with us. Find someone who specialises in Mercedes, then it’ll get mended.