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Would love it if someone could offer some advice please as I'm at a loss as to where to go next!
About 3 weeks ago the wife's 05 reg C220 Cdi went into limp mode with no warning lights showing.
Put my diagnostic set on and it had no stored codes but did have a Pending: P0299 code turbo underboost. Checked all pipes, connections etc leading to turbo and no obvious sign of any issues. Cleared code and it continued to run OK for about 3 weeks.
Two days ago it went into limp mode again. Still no dash warning light.
Diagnostics showed no stored codes again, although it did have pending codes.
This time they were: P2084 Exhaust Gas Temperature EGT Sensor Circuit Range Bank 1 Sensor 2 P0299 Turbocharger Underboost P2080 EGT Sensor Circ Performance Bank 1 Sensor 1
Unsure what to do about this I cleared all codes and set about doing a little research - not too successfully so far!
Today, took the car for a bit of a run and after about 20 miles the engine management light came on and it went into limp mode again.
This time diagnostic had one stored & one pending code: Stored: P2A00 O2 Sensor Circuit Range/Performance Bank 1 Sensor 1 Pending: P0299 Turbocharger Underboost
Whilst I'm generally handy enough to do the work myself I am somewhat stuck as to where to start with fixing this! Really don't want to just swap parts at random as that's a very expensive way to fault find and simply not an option on such an old car.
Any advice would be truly appreciated Thanks
Last edited by HaloJones; Sep 13, 2019 at 06:56 AM.
Most likely the problem is with turbo actuator. Most common issue is worm gear is worn out and/or broken electrical connection.
If you know how to solder it is easy and cheap fix.
I didn't want to cloud the issue but after the first code came up (Pending: P0299 code turbo underboost. Checked all pipes, connections etc leading to turbo and no obvious sign of any issues.) I did replace the intake pipes(below), although ultimately this seemed to have no effect, therefore I didn't mention this - suppose I should have.
Replaced this
No other work has been done or replaced since.
Last edited by HaloJones; Jul 10, 2019 at 06:28 AM.
On OM642 engine is very common that electrical connection on turbo actuator is broken (see photo below). You can open the actuator and check the connection. It's easy and free fix if you know how to solder.
@artim808 - Thanks for that. I don't have the OM642 engine but I will have a look and see if there is a similar set-up and issue. Will have to be over the weekend now.
Appreciated
Couldn't get anywhere myself so finally took it to a MB specialist.
Problem found to be that the N/S lower turbo boost pipe had a 2 inch split in it!
Pipe is tucked away somewhat but the mechanic said he could hear it sucking if someone else was throttling at the same time.
Hope that helps if you find you have a similar problem...
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