Fault code P0048 – a step-by-step guide to diagnosing and fixing it

Error code P0048 is displayed and the check engine light is on - what does this mean?

The OBD system detects a fault in the turbocharger/compressor bypass valve control circuit, which indicates a low signal level. This DTC P0048 relates to the wastegate system of the turbocharger and can be interpreted differently by different manufacturers, although the focus is always on the basic function of the boost pressure control system.

What causes can this error code have?

• Defective turbocharger bypass valve (wastegate)
• Damaged or interrupted cable to the wastegate actuator
• Loose or corroded plug connections
• Defective wastegate actuator or servomotor
• Vacuum hose leaks in the boost pressure system
• Faulty engine control unit software
• Defective boost pressure sensor
• Mechanical defect on the turbocharger wastegate

What symptoms occur in parallel with error code P0048?

• Loss of power: The vehicle shows significantly reduced engine power, especially under load
• Black smoke: Black smoke comes out of the exhaust, especially when accelerating
• Irregular idling: The engine runs unevenly or stutters when idling
• Whistling noises: Unusual whistling or hissing noises from the engine compartment
• Increased fuel consumption: Significantly higher fuel consumption than usual
• Starting problems: Difficulty starting, especially when the engine is cold

How can I fix the problem with error code P0048?

• Repairing trouble code P0048 requires a systematic approach to identify the source of the fault.
• Inspection and replacement of the wastegate actuator and wiring, including a functional test of the entire boost pressure control system
• Complete inspection and repair of all vacuum hoses and connections in the turbocharger system with subsequent leak test
• Cleaning or replacement of the turbocharger bypass valve and checking the mechanical mobility of all components
• Diagnosis and repair of the electrical connections to the engine control unit, including resistance measurement and voltage test
• Software update of the engine control unit or complete reprogramming according to the manufacturer's specifications
• Replacement of the boost pressure sensor with subsequent calibration and system test