What it means
The turbocharger or supercharger boost control A circuit is reporting voltage below the expected range.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Boost Control A is the electrical circuit the module uses to operate the turbocharger or supercharger boost-control actuator or solenoid. The module monitors the circuit voltage while commanding boost control. P0047 sets when the Boost Control A circuit voltage is below the expected range, often because a wire is shorted to ground or a connection has excessive resistance.
Common causes
Most likely first.
- Wiring shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Reduced engine performance
How to diagnose it
- Read freeze-frame data and live boost-control data to identify when the Boost Control A circuit went low and whether boost response also changed.
- Inspect the Boost Control A connector and nearby harness for chafing, heat damage, moisture, corrosion, or contact with ground.
- Check the circuit fuse and power supply, then compare voltage and control-side readings with the manufacturer's specification.
- Test the Boost Control A wiring for a short to ground and check connector terminals for excessive resistance or poor contact.
- Test the actuator or solenoid and module control output according to the manufacturer's procedure if the wiring checks pass.
Common fixes
- Repair Boost Control A wiring that is chafed and shorted to ground.
- Clean or repair corroded connector pins and restore good terminal contact.
- Repair a failed fuse or supply connection after finding and correcting its cause.
- Replace the Boost Control A solenoid or actuator if it fails the specified test.
Can I keep driving?
Reduced power or limp mode can make acceleration unpredictable, so avoid towing, hard acceleration, and high-speed overtaking until the circuit is checked. Stop safely if power drops sharply or the engine develops unusual turbo noise or smoke.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.