'08 ML 320. DTC P0299. Any input appreciated
Here's the low-down. I recently bought an '08 ML320 CDI and it ran beautifully for the first two weeks and now it's acting up. First, there was a check engine light and it went into limp mode. I did a diagnostic check - DTC P0299, Underboost condition, so I replaced the fuel filter and erased the trouble code with the diagnostic tool to see if it would reset the limp mode... It didn't. Still had no power.
The next day I start it up and it's running really rough and died just pulling it out of the garage so I just limped it back in and now here I am.
Was it a mistake to clear the code? I just thought if the problem wasn't fixed that it would just show the check engine light again but now it's much worse.
Any ideas where I should start? I'm new to Mercedes and diesel at the same time so I'm biting off a lot here, I know, but I'm fairly mechanically inclined so I'm confident... I just need some help getting started.
Thanks, in advance, for any help offered.
Justin
All I had done at that point was removed all of the air ducting around the turbo i.e. filters and housing, ducting to and from the turbo but the key was the sensors.
I assembled everything except the sensors and plugged them in one by one and located the problem... The MAP sensor on the housing of the driver side filter. It's on order. If I get it and it's not the solution, I'll report back.
Hope that helps someone.
The part came in today, I installed it but the car was still in limp mode. I disconnected the battery and let it sit for about an hour and reconnected but now the check engine light is back on and it drives with severe spurts. I'll have to get another diagnostic tool and see what it reads.
Any suggestions?

Mine is bringing up the same code . but only goes into limp mode when push it to 160km/h.
The part came in today, I installed it but the car was still in limp mode. I disconnected the battery and let it sit for about an hour and reconnected but now the check engine light is back on and it drives with severe spurts. I'll have to get another diagnostic tool and see what it reads.
Any suggestions?
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