What it means
Turbocharger or supercharger boost control A is not operating within the expected range or performance limits.
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 turbocharger or supercharger control system the module uses to regulate boost pressure. It monitors commanded operation and the resulting boost-control response. P0046 sets when that response falls outside the expected range or performance limits, which can occur with a leaking boost or vacuum line, a sticking wastegate, or an inaccurate sensor.
Common causes
Most likely first.
- Vacuum/boost line leak
- Wastegate sticking
- Sensor element aged beyond calibration window
Symptoms
- Check engine light on
- Reduced engine performance
How to diagnose it
- Use freeze-frame data and live data to compare commanded boost with measured boost when the fault occurs.
- Inspect Boost Control A hoses and lines for leaks, loose connections, splits, or collapse.
- Check the wastegate and boost-control actuator linkage for binding or signs that the mechanism is sticking, following safe manufacturer procedures.
- Inspect the boost-pressure sensor and its wiring and compare its readings with other available engine data.
- Test the Boost Control A actuator, solenoid, and sensor response using the manufacturer's procedure to isolate a control or calibration fault.
Common fixes
- Reconnect or replace a leaking or damaged boost or vacuum line.
- Repair a sticking wastegate or boost-control linkage if inspection confirms binding.
- Repair damaged wiring or a poor connection at the Boost Control A sensor or actuator.
- Replace the failed actuator, solenoid, or sensor only after testing identifies it as the cause.
Can I keep driving?
The vehicle may have reduced power or enter limp mode, so avoid hard acceleration, towing, and situations where sudden loss of power would be hazardous. Stop driving if boost problems are accompanied by smoke, unusual mechanical noise, or a rapid loss of power.
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.