Turbocharger Boost Control Position Sensor Circuit Low

Possible causes

• CommonVariable-vane mechanism sticking with soot, on a diesel
• CommonFailed boost control position sensor
• CommonCorroded connector or wiring damaged by exhaust heat
• CommonActuator linkage worn, disconnected or seized
• PossibleLoss of reference voltage or earth
• PossibleFailed actuator motor

What you might notice

• Reduced power or limp mode
• Poor acceleration
• Excessive smoke on a diesel
• Whistling or fluttering from the turbo
• Check engine light on

What to check, in order

1. Check the actuator linkage moves freely. On a diesel used mainly for short journeys, soot seizing the variable-vane mechanism is extremely common and cleaning is often the whole repair.
2. Watch commanded against actual boost control position on the live data screen through a sweep.
3. Inspect the connector for corrosion and heat damage.
4. Check the reference voltage and earth at the sensor.
5. Suspect the turbocharger itself last - it is by far the most expensive item and by far the least likely cause of a position sensor code.