Turbocharger
Check gas exchange system of leakage. If available , perform the check " Leakage test of the EGR system "" in SDP3. Check boost pressure sensor ( T122 ) with ignition on and the engine off Check the air filter Check the intercooler Check the exhaust back pressure sensor T125 , the boost pressure sensor T122 and boost temperature sensor T121 , mass flow sensor ( T126 ) . Check for error codes related to the exhaust brake / pressure sensor / DPF ( clogged ) Check the exhaust brake valve can move freely Check the turbocharger and its electric motor. Gas engine: Check throttle M34 Check the dump valves V189, V190, and the control for these works Check wastegate valve V109 and boost pressure sensor T47. Note Always perform a resetting of adaptation values of the mass air flow sensor if the mass air flow sensor is replaced, or if a leak in the engine intake system have been fixed To verify that the error is fixed requires driving with a full load for a few minutes
What you'll see
No driver-visible symptom recorded.
System reaction
Engine torque/power might be reduced. Black smoke might occur, visible for engines without DPF.
Diagnostic depth
Actual boost pressure is less than requested boost pressure by more than the permitted tolerance
Possible causes: • Leakage in gas exhange system • Faulty boost pressure sensor (T122) • Clogged air filter. • Clogged intercooler • MAF adaption has incorrectly low values • Incorrect values from the exhaust back pressure sensor T125, boost pressure sensor T122, boost pressures temperature T121, mass air flow sensor T126 • Too high back pressure on the exhaust side eg exhaust brake is closed or clogged DPF, faulty exhaust pressure sensor • Turbocharger defective (compressor or turbine) - inclusive faulty wastegate or VGT control Gas engine: • Leakage in gas exchange system • Wastegate valve is stuck in the open position. • The control valve to the wastegate actuator is broken • The dump valve is stuck in the open position (V189 ) • Boost pressures shows incorrect value.