What does it mean?
Here the turbocharger outlet pressure sensor is electrically healthy, but the pressure it reports does not agree with what the engine is actually doing. With the engine off the sensor should read barometric pressure, and while driving its value should track commanded boost and the manifold pressure signal. The module stores this code when the reading is stuck, slow, offset by a constant amount, or fails to rise when the turbocharger is clearly building pressure. Because the test compares the sensor with real engine behaviour, it can also be triggered by a genuine boost problem such as a leaking charge air system or a sticking wastegate.
Symptoms
- Reduced power and slow acceleration, sometimes with the boost display behaving oddly
- Boost that overshoots then cuts, or surges up and down under steady load
- limp mode after a hard pull on some vehicles
- Black smoke and a strong exhaust smell on diesels
- MIL on, often together with boost control or manifold pressure codes
- Higher fuel consumption and poor performance on hills
Likely causes
- Pressure port or sensor tip clogged with soot, oil or carbon so the sensor responds slowly
- Water or ice trapped in the sensor port, particularly on short winter journeys
- Sensor element drifted so the reading carries a constant offset
- Charge air leak from a split hose, loose clamp or failed intercooler, so real boost never reaches target
- Wastegate or variable vane mechanism sticking, giving boost that does not follow the command
- Restricted intercooler or charge pipe creating a genuine pressure difference along the system
- Manifold or barometric pressure sensor used for the comparison reading incorrectly
How to fix it
- With the key on and the engine off, compare the sensor with barometric pressure; any difference at rest is a direct sign of offset or blockage
- Graph outlet pressure against manifold pressure and commanded boost during a snap acceleration and look for lag, clipping or a fixed gap
- Remove the sensor and inspect its port and tip for soot, oil, water or ice, and clear the passage
- Pressure test or smoke test the charge air system from the compressor to the throttle to find leaks
- Check the wastegate or vane actuator for free movement and correct response to command
- Inspect the intercooler and charge pipes for internal restriction or oil accumulation
- Replace the sensor with the correct specification part only after the charge air system and reference sensors are proven