V6 diesel from ML, GL, E Class and Sprinter. EGR and swirl flaps clog up, and the oil cooler seals famously leak.
Click a code for the full breakdown: symptoms, causes, and whether you can keep driving.
Turbocharger Underboost
The turbo is producing less boost pressure than the ECU requests.
Diesel Particulate Filter Efficiency Below Threshold
The DPF is not trapping soot as it should - it may be damaged, removed, or overloaded.
EGR Flow Insufficient
The exhaust gas recirculation valve is not flowing enough exhaust back into the intake, usually due to carbon buildup.
Fuel Rail/System Pressure Too Low
Measured fuel pressure is below what the ECU commands - the engine may be starved of fuel under load.
Glow Plug Module Control Circuit (Diesel)
The control circuit of the diesel glow plug module has a fault.
Turbocharger Overboost Condition
Boost pressure exceeded the safe limit - the wastegate or boost control is not relieving pressure.
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