The most popular diesel in Europe (Golf, Passat, Octavia, A4). With age the EGR, DPF and dual-mass flywheel show up; the CR injection outlasts the old unit injectors.
Click a code for the full breakdown: symptoms, causes, and whether you can keep driving.
EGR Flow Insufficient
The exhaust gas recirculation valve is not flowing enough exhaust back into the intake, usually due to carbon buildup.
Diesel Particulate Filter Efficiency Below Threshold
The DPF is not trapping soot as it should - it may be damaged, removed, or overloaded.
Turbocharger Underboost
The turbo is producing less boost pressure than the ECU requests.
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.
System Voltage Low
The ECU sees battery/system voltage below normal while the engine runs.
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