Powertrain, generic (extended)

P2581 Turbocharger/Supercharger Speed Sensor A Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2581 is set when speed sensor A reports a level above what a healthy circuit can produce, so the engine computer cannot trust it. Typical triggers are a signal wire shorted to the supply or battery voltage, an open signal or ground path that lets the input float high, or a sensor with a shorted output stage. No manufacturer documents P2581 publicly; the closest evidence is Bentley's W12 bulletin, which lists the B-sensor high fault P2596 and demands checks for shorts to B+ before the sensor is replaced, and CARB's rule that electronic boost-control parts be monitored as comprehensive components. P2580 is the low-side fault, P2582 brief dropouts. The engine usually trims boost and lights the warning lamp.

Likely causes

Signal wire shorted to supply or battery voltage
Open ground or signal wire letting the input float high
Speed sensor A with a shorted output

Symptoms

  • Malfunction indicator lamp on
  • Implausibly high or fixed turbo speed in live data
  • Reduced boost and power

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–500
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

turbo speed sensor asensor wiring

Related codes

P2578P2579P2580P2582P2596

References: law.cornell.edu, static.nhtsa.gov.