Powertrain
generic / SAE
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.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 78
Possible causes
- Open or shorted wiring high
- Aged sensor with reduced output amplitude medium
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 200–1000 €
- Estimated time: 0.6–2.5 h
- Component: turbo speed sensor a
- Component: sensor wiring
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012