What it means
Supply voltage feeding boost control actuator B is below the expected range. Likely fuse, supply wiring or relay fault.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Boost control actuator B adjusts turbocharger or supercharger boost, and its supply circuit provides the electrical power it needs. The control module monitors that supply and sets P005E when the voltage feeding actuator B is below the expected range, often because of a fuse, relay, connector, or wiring fault.
Common causes
Most likely first.
- Supply fuse blown or relay failed
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Reduced engine power or acceleration, if boost control is affected
How to diagnose it
- Save freeze-frame data and scan for other boost-control or supply-voltage codes that could identify a shared power problem.
- Identify actuator B from the vehicle wiring information, then inspect its connector and harness for corrosion, loose pins, chafing, or heat damage.
- Check the actuator B supply fuse and relay, if fitted, for a failed component or poor contact; determine why a fuse failed before replacing it.
- Measure supply voltage at actuator B under the manufacturer's specified test conditions and compare the result with the manufacturer's specification.
- If the supply path passes, test the actuator B circuit and actuator using the manufacturer's procedure to locate a wiring or component fault.
Common fixes
- Restore a poor or corroded connection at the boost control actuator B connector.
- Replace a confirmed failed supply fuse or relay after checking for the cause of failure.
- Repair chafed, open, or high-resistance wiring in the actuator B supply circuit.
- Replace or repair the actuator B only if the specified circuit tests confirm it has failed.
Can I keep driving?
Treat reduced power or limp mode as a reason to avoid overtaking, steep climbs, and towing; arrange diagnosis promptly. Do not continue driving if the engine behaves unpredictably or loses power in a hazardous situation.
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.