Capteur de position d'ailettes de turbocompresseur défectueux

The sensor reporting where a variable-geometry turbocharger's vanes actually are, so the module can check that they went where it asked. It is named by more codes than almost anything else on a modern diesel, and it is right far less often than it is replaced.

The reason is that the code says the feedback is wrong, and there are four ways for that to happen with only one of them being this part: the vanes did not move because carbon has bound them, the actuator did not push because it or its vacuum supply has failed, the wiring between sensor and module has been cooked by the housing it is strapped to, or the sensor itself is lying. Three of those four are cheaper than this one, and on many vehicles the sensor is not separately available at all — it is integrated into the actuator, so "replace the sensor" quietly means replacing the actuator.

The test that settles it is a graph, not a multimeter. Command the vanes through their full travel with a scan tool and watch commanded against actual: a trace that follows the command exonerates the sensor outright, one that lags or falls short points at the mechanism, and one that does not move at all points at the actuator or a seized mechanism. That takes minutes and routinely saves the part.

One trap worth naming: after any work on the turbo or actuator, the actuator must relearn its end stops. Skip that and the feedback disagrees with the command permanently, on hardware that is now perfect — which is how a good repair gets diagnosed as a failed part and a second one gets fitted.