Fault code P0240 – a step-by-step guide to diagnosing and fixing it

Error code P0240 is displayed and the check engine light is on - what does this mean?

The OBD system detects a fault in the turbocharger boost sensor circuit "B", which is responsible for monitoring the boost pressure. This DTC P0240 trouble code mainly affects the turbocharging system and the associated sensors. For various manufacturers, this fault code may also be referred to as "Turbocharger/Supercharger Boost Sensor B Circuit".

What causes can this error code have?

• Defective turbocharger boost sensor B
• Damaged wiring to the boost sensor
• Corroded or loose plug connections
• Defective turbocharger control unit
• Blocked or leaking vacuum lines
• Faulty engine control unit (ECU)
• Mechanical defect on the turbocharger
• Defective wastegate or bypass valve

What symptoms occur in parallel with fault code P0240?

• Loss of power: Significantly reduced engine power, especially under load
• Poor acceleration: The vehicle accelerates hesitantly or jerks
• Increased fuel consumption: Noticeably higher consumption than usual
• Irregular idling: Engine runs unevenly or stutters at idle speed
• Black smoke: Dark exhaust fumes from the exhaust, especially when accelerating
• Whistling or hissing: Unusual noises coming from the engine compartment

How can the problem with error code P0240 be rectified?

• The repair requires a systematic approach to identify and rectify the cause.
• Replace boost sensor B: Locate the defective turbocharger boost sensor, remove it and replace it with a new original part, then clear the fault code and carry out a test drive
• Repair wiring: Check all cables to the boost sensor for damage, repair or replace defective cables, clean plug connections and treat with contact spray
• Replace vacuum lines: Check all vacuum lines to the turbocharger and boost sensor for cracks or leaks and completely replace damaged hoses
• Replace turbocharger control unit: If the electronic control unit is defective, replace it with a new or overhauled unit and then have it programmed
• Complete turbocharger overhaul: In the event of mechanical damage to the turbocharger, carry out a general overhaul or replace the entire unit
• ECU diagnosis and repair: Have the engine control unit checked for defects and, if necessary, repaired or replaced with a programmed replacement unit