P0048–P004D Turbocharger/Supercharger Boost Control A Circuit High
The voltage on this circuit is sitting near battery voltage. Typically a short to a positive feed, or a disconnected sensor floating high.
Can you drive it? The car is most likely in limp mode with boost cut. It is drivable gently, but it will not make full power and should not be driven hard until it is fixed.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
P0048 | Turbocharger/Supercharger Boost Control A Circuit High | Investigate soon |
P004D | Turbocharger/Supercharger Boost Control B Circuit High | Investigate soon |
The definition
P0048: Turbocharger/Supercharger Boost Control A Circuit High.
P0048 is a powertrain code (the engine or gearbox), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.
What to check first
Cheapest and fastest checks first:
- Unplug the sensor and check whether the signal falls. If it stays high, suspect the wiring rather than the sensor.
- Check the earth path - a missing earth makes a sensor read high.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
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Common questions
What does P0048 mean?
P0048 means Turbocharger/Supercharger Boost Control A Circuit High. The voltage on this circuit is sitting near battery voltage. Typically a short to a positive feed, or a disconnected sensor floating high.
Can I drive with P0048?
The car is most likely in limp mode with boost cut. It is drivable gently, but it will not make full power and should not be driven hard until it is fixed.