OBD-II code · Powertrain (generic, extended)
P2578 Turbocharger/Supercharger Speed Sensor A Circuit
General electrical fault on the turbocharger/supercharger shaft speed sensor A — a high-frequency Hall or eddy-current sensor on the compressor shaft. The ECM uses turbo speed for overspeed protection (typically 200,000+ rpm) and for closed-loop boost on VGT systems. With no valid speed the ECM limits boost.
Is it safe to drive with P2578?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen or shorted wiring
- PossibleAged sensor with reduced output amplitude
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.6–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Turbo Speed Sensor A, Sensor Wiring
Related codes
- P2575Direct Ozone Reduction Catalyst Deterioration Sensor Circuit High
- P2576Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Intermittent/Erratic
- P2577Direct Ozone Reduction Catalyst Efficiency Below Threshold
- P2579Turbocharger/Supercharger Speed Sensor A Circuit Range/Performance
- P257AVacuum Reservoir Control Circuit/Open
- P257BVacuum Reservoir Control Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.