What does it mean?
Here the turbocharger outlet pressure signal is usually inside its normal range, yet it flickers, drops out or swings in a way real boost pressure cannot. The module monitors the input for continuity and for unrealistic rates of change alongside the fixed high and low limits, and stores this code when the signal behaves erratically. Boost control depends on a steady feedback value, so every drop-out forces the module to react to a false pressure for a moment. Because the fault is only present now and then, the lamp and the power loss may come and go over several journeys.
Symptoms
- MIL that appears and disappears over several drive cycles
- Momentary power loss or a hesitation under boost with no warning
- Boost pressure value visibly jumping on a scan tool while conditions are steady
- Occasional limp mode that clears after a restart
- Uneven pulling on long hills and an inconsistent feel from the same gear and load
- Occasional smoke on diesels as fuelling briefly mismatches the real airflow
Likely causes
- Loose or spread terminals in the sensor or module connector
- Chafed harness touching a metal edge or another circuit as the engine moves on its mounts
- Water or corrosion in the connector giving a resistance that changes with heat and vibration
- Cracked sensor element that opens intermittently once it reaches operating temperature
- Poor sensor ground that only shows up under electrical load
- Harness stretched tight over a bracket so movement stresses the conductors
- Damage to the wiring from heat radiating off a nearby charge pipe or the turbocharger
How to fix it
- Review the freeze frame to learn whether the drop-outs happen when hot, on rough surfaces or under heavy boost
- Graph the sensor signal live and wiggle the connector and harness with the engine running and again while it is warm
- Use a scope where possible, since a very short interruption may never appear on a scan tool display
- Measure voltage drop on the reference and ground circuits while flexing the harness
- Open and inspect the connector for moisture, corrosion and terminals that no longer grip firmly
- Repair chafed insulation, renew poor terminals and re-route the harness away from heat and movement
- Replace the sensor last, after the wiring is proven good and the instability clearly follows the sensor