between each gear it had to reach 2600rpm before it wd change. But it wdnt go any higher than 5th ear.

[tombell]

Got a 2012 ML250 - today all was fine travelling along the A34 when the engine wdnt accelerate. After a while I switched to M (Flappy paddles) so that I cd see what gear I was in. (I didn't use the flappy paddles - Just drove along as though I was in automatic) . I worked out, that from standing start it was only changing up (pretty revvy) when the revs reached 2600rpm.g So between each gear it had to reach 2600rpm before it wd change. But it wdnt go any higher than 5th ear. So I got home doing 55 in 5th.
For the first time ever I connected an ODB reader (Cheap one from MOTOPOWER) and got PO299 TURBO CHARGER UNDERBOOST.
Does this mean I need a new Turbo?

 

[toteimerced]

More likely a split intercooler hose.

 

[tombell]

Also got the P2463 fault code - Occurs due to excessive soot accumulation in the Diesel Particulate Filter (DPF).
Not sure that this is the fault as I drive pretty quickly wherever i go - Usually 70ish on dual carriageways at least twice a week

 

[DSM10000]

Got a 2012 ML250 - today all was fine travelling along the A34 when the engine wdnt accelerate. After a while I switched to M (Flappy paddles) so that I cd see what gear I was in. (I didn't use the flappy paddles - Just drove along as though I was in automatic) . I worked out, that from standing start it was only changing up (pretty revvy) when the revs reached 2600rpm.g So between each gear it had to reach 2600rpm before it wd change. But it wdnt go any higher than 5th ear. So I got home doing 55 in 5th.
For the first time ever I connected an ODB reader (Cheap one from MOTOPOWER) and got PO299 TURBO CHARGER UNDERBOOST.
Does this mean I need a new Turbo?

No.

It could well be a split or detached hose causing low boost


Don't rely on basic OBD scanners. It is having the knowledge to interpret the code that is more important than the code itself.

Have a look at all of the hoses to and from the Intercooler (engine off and preferably cold). The splits can be hard to see unless under pressure but careful inspection should help.

 

[toteimerced]

Under boost will also prevent regeneration of the dpf.

 

[tombell]

More likely a split intercooler hose.

Thanks for the suggestion toteimerced.
Cd be as I used to have a 2012 E220 Diesel which had a split hose but it never exhibited having to reach 2600rpm between changing up thru the gears and it drove normally unless i floored it - Then it wd "Go Fast" "Go Slow".

 

[tombell]

No.

It could well be a split or detached hose causing low boost


Don't rely on basic OBD scanners. It is having the knowledge to interpret the code that is more important than the code itself.

Have a look at all of the hoses to and from the Intercooler (engine off and preferably cold). The splits can be hard to see unless under pressure but careful inspection should help.

Thanks for that DSM10000 - I'll check the hoses

 

[DSM10000]

Thanks for that DSM10000 - I'll check the hoses/

Thanks for that DSM10000 - I'll check the hoses

I would also check where the MAF and pipework connect to the Turbo

 

[tombell]

Under boost will also prevent regeneration of the dpf.

Thanks again, as I;m guessing my DPF is in fairly good condition as I drive quite quickly on motorways a couple of times a week

 

[tombell]

I would also check where the MAF and pipework connect to the Turbo

OK - Thanks DSM

 

[ALFAitalia]

Does this mean I need a new Turbo?

It did in my case....I had the exactly same symptoms on my similarly powered E350 CDI. Not a difficult DIY job if you do need a turbo......as its on top of the engine although I suspect access might be more difficult in your vehicle that mine.

Take off the intake batwing and check for blade damage and excessive front to rear or side to side play.....my blades were damaged and the side to side play was such that the blades could hit the housing!!

Hopefully it will just be a hose leak....the far cheaper option and you wont have a turbo that looks like this!!

 

[Pontoneer]

Got a 2012 ML250 - today all was fine travelling along the A34 when the engine wdnt accelerate. After a while I switched to M (Flappy paddles) so that I cd see what gear I was in. (I didn't use the flappy paddles - Just drove along as though I was in automatic) . I worked out, that from standing start it was only changing up (pretty revvy) when the revs reached 2600rpm.g So between each gear it had to reach 2600rpm before it wd change. But it wdnt go any higher than 5th ear. So I got home doing 55 in 5th.
For the first time ever I connected an ODB reader (Cheap one from MOTOPOWER) and got PO299 TURBO CHARGER UNDERBOOST.
Does this mean I need a new Turbo?

If you've only recently bought the vehicle ( your opening sentence reads as though you might have ) , then as long as you bought it from a dealer or a trader of some sort , you can take it back to them and ask them to fix it .

Under the consumer rights act , they have to do this , or give a refund , if you bought it within the last 30 days , up to six months from sale , they still have to fix it .

 

[tombell]

If you've only recently bought the vehicle ( your opening sentence reads as though you might have ) , then as long as you bought it from a dealer or a trader of some sort , you can take it back to them and ask them to fix it .

Under the consumer rights act , they have to do this , or give a refund , if you bought it within the last 30 days , up to six months from sale , they still have to fix it .

Thanks for the advice Pontoneer but I have had this car for 4 years. Sorry for the confusion.

 

[tombell]

It did in my case....I had the exactly same symptoms on my similarly powered E350 CDI. Not a difficult DIY job if you do need a turbo......as its on top of the engine although I suspect access might be more difficult in your vehicle that mine.

Take off the intake batwing and check for blade damage and excessive front to rear or side to side play.....my blades were damaged and the side to side play was such that the blades could hit the housing!!

Hopefully it will just be a hose leak....the far cheaper option and you wont have a turbo that looks like this!!

View attachment 171105

Thanks ALFAitalia but I'm not that technical - I'm looking for a MB engineer around Oxford right now

 

[tombell]

I took it for a short run yesterday to see if it wd respond to the flappy paddles (Which I never use normally) but no go. Didn't matter if I tried to change up or down - nothing happened

 

[Pontoneer]

Thanks ALFAitalia but I'm not that technical - I'm looking for a MB engineer around Oxford right now

I'm sorry I can't advise re anyone in that area , as I'm in Scotland .

However there is a section on this forum re MB Specialists near where you are . Could be worth scanning through there .

Mercedes specialists across the UK

Found it difficult to locate good, affordable Mercedes specialists? Find out or talk about your experiences with Mercedes specialists in your area.

forums.mbclub.co.uk

 

[tombell]

I'm sorry I can't advise re anyone in that area , as I'm in Scotland .

However there is a section on this forum re MB Specialists near where you are . Could be worth scanning through there .

Mercedes specialists across the UK

Found it difficult to locate good, affordable Mercedes specialists? Find out or talk about your experiences with Mercedes specialists in your area.

forums.mbclub.co.uk

Thanks Pontoneer - I'll check it out.

 

[tombell]

I'm waiting for mobile BENZTECH engineer to respond so had a look under the bonnet.
From my point of view, standing in front of the ML250 I can see what looks like a 1.5 inch thick hose to the right hand side of the engine with a 3 or 4 inch thick hose below it which has a 6 inch split in the rubber showing the inner fabric.
Tried to stick some gaffer tape over it just to see if that was the problem but it wdnt stick.
Do you think this may be the problem?

 

[tombell]

No.

It could well be a split or detached hose causing low boost


Don't rely on basic OBD scanners. It is having the knowledge to interpret the code that is more important than the code itself.

Have a look at all of the hoses to and from the Intercooler (engine off and preferably cold). The splits can be hard to see unless under pressure but careful inspection should help.

I'm waiting for mobile BENZTECH engineer to respond so had a look under the bonnet.
From my point of view, standing in front of the ML250 I can see what looks like a 1.5 inch thick hose to the right hand side of the engine with a 3 or 4 inch thick hose below it which has a 6 inch split in the rubber showing the inner fabric.
Tried to stick some gaffer tape over it just to see if that was the problem but it wdnt stick.
Do you think this may be the problem?

 

[DSM10000]

I'm waiting for mobile BENZTECH engineer to respond so had a look under the bonnet.
From my point of view, standing in front of the ML250 I can see what looks like a 1.5 inch thick hose to the right hand side of the engine with a 3 or 4 inch thick hose below it which has a 6 inch split in the rubber showing the inner fabric.
Tried to stick some gaffer tape over it just to see if that was the problem but it wdnt stick.
Do you think this may be the problem?

I would say so!

The pressure is to high for any such repair