W164 engine power issue

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SimonAt

New Member
Joined
Jul 14, 2019
Messages
6
Location
Wales
Car
Mercedes ML300CDI (W164)
Hi all.
I'm running a 2011 ML300CDI (W164.121) which has recently suffered a loss of power. I don't think it's in limp mode but from a standstill it accelerates very slowly. Once it gets to 3rd gear and above 2000 revs it behaves normally. It changes gear automatically at the right time and I can force manual changes too with no issue.
The issue has been present for 3-4 weeks now. About 10 days after the original loss of power the engine light came on and reported a P0400/P0405 issue so I cleaned the EGR, firstly by using cleaner spray directly into the intake (made no difference) and then removed and de-coked the EGR completely. Whilst I was there I also cleaned the MAF sensors just in case. Cleared codes and they haven't returned but this hasn't made any difference.
Worth mentioning that in the past couple of days the fan has started spinning at maximum revs from the moment you turn the key, even on a cold engine. After shutting off the engine it continues to run for a few minutes. All the while, the engine temp remains low. Not sure if this is a separate issue/red herring?
I'm now thinking about next steps and my current thinking is to move onto:
1 - the turbo wastegate (possibly sticking open?)
2 - a more significant turbo failure?
3 - inlet port shut off motor faulty? (wondering about this because the rubber seal around the turbo air intake is split and there's some fouling form the exhaust gas return pipe.
Ideas much appreciated. Thanks
 
Hi all.
I'm running a 2011 ML300CDI (W164.121) which has recently suffered a loss of power. I don't think it's in limp mode but from a standstill it accelerates very slowly. Once it gets to 3rd gear and above 2000 revs it behaves normally. It changes gear automatically at the right time and I can force manual changes too with no issue.
The issue has been present for 3-4 weeks now. About 10 days after the original loss of power the engine light came on and reported a P0400/P0405 issue so I cleaned the EGR, firstly by using cleaner spray directly into the intake (made no difference) and then removed and de-coked the EGR completely. Whilst I was there I also cleaned the MAF sensors just in case. Cleared codes and they haven't returned but this hasn't made any difference.
Worth mentioning that in the past couple of days the fan has started spinning at maximum revs from the moment you turn the key, even on a cold engine. After shutting off the engine it continues to run for a few minutes. All the while, the engine temp remains low. Not sure if this is a separate issue/red herring?
I'm now thinking about next steps and my current thinking is to move onto:
1 - the turbo wastegate (possibly sticking open?)
2 - a more significant turbo failure?
3 - inlet port shut off motor faulty? (wondering about this because the rubber seal around the turbo air intake is split and there's some fouling form the exhaust gas return pipe.
Ideas much appreciated. Thanks

An update. When I turned the vehicle on today (having done no work since the last post) and plugged in the scanner it reported:
P0112 - Intake Air Temp Sensor Circuit Low
P2002 - DPF Efficiency below threshold
P0102 - MAF Circuit Low
P0405 - EGR Sensor Circuit Low
 

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