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Have a bone stock 2015 63s just rolled 75k mi . Check engine popped up today with an underboost code p0299.Car doesn't feel down on power.
Searched but only found a minimal amount of info. Looks like either a boost leak or the transducer pressure sensor. Looks like a smoke test may be in order as well. If anyone else has ran into this - any info is appreciated.
Last edited by SilverE5588; 06-03-2021 at 10:43 PM.
Just an update if anyone runs into this. Swapped out the boost pressure solenoid & the 2 vac lines that run down to the wastegate actuators. They looked to have some rub wear in the tight spots.
Local mb dealer stocked one of the vac lines and the solenoid - took that as a good sign. So far so good after replacement.
May have spoke too soon . Code p0299 has returned , guess a smoke test is in order . Are any of these couplers more common then another to be a leak source culprit ? visual check is all ok , wastegates both actuate on startup .
Just an update on this P0299 underboost code that returned after replacing the boost solenoid & vac. lines running to it . This code seems to be evasive in some cases I found upon searching . Seemed to take mb a little while to figure out the issue as well . Issue was both waste rods looser then spec , and turbocharger 1 rod was missing the "c"clip that secures it onto the lever of some sort.They replaced the clip and adjusted rods . So far so good ..
Not sure how common this is or isn't, came across this a few other times searching so maybe not that rare . Some were in m157 based suv's, but very similar i'm guessing.
Last edited by SilverE5588; 07-12-2021 at 10:35 PM.
Just an update on this P0299 underboost code that returned after replacing the boost solenoid & vac. lines running to it . This code seems to be evasive in some cases I found upon searching . Seemed to take mb a little while to figure out the issue as well . Issue was both waste rods looser then spec , and turbocharger 1 rod was missing the "c"clip that secures it onto the lever of some sort.They replaced the clip and adjusted rods . So far so good ..
Not sure how common this is or isn't, came across this a few other times searching so maybe not that rare . Some were in m157 based suv's, but very similar i'm guessing.
What ended up happening? I just threw the same code today and am curious of the outcome.
What ended up happening? I just threw the same code today and am curious of the outcome.
The wastegate actuator rod clips apparently loosen up & come off in some cases like mine.Tricky because the rods still stayed in place so they would semi actuate - but had no tension on them . Clips were sourced from mb and replaced in car by massaging the heat shields up a little to access .
Last edited by SilverE5588; 04-18-2023 at 09:45 PM.
06-02-2021, 12:27 AM
