What it means
The turbocharger/supercharger boost control A module is not performing as expected.
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
The boost control A module manages turbocharger or supercharger boost and reports its operating status to the control module. This code sets when A's performance does not match the commanded or expected operation; it points to the A module, its software, or its power supply rather than identifying a specific mechanical boost fault.
Common causes
Most likely first.
- Boost control module internal fault
- Module software outdated, reflash may resolve
- Supply voltage outside specification
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Save freeze-frame data and check for related boost or voltage codes to see when the A module fault occurred and whether other faults may explain it.
- Use a scan tool to compare commanded and reported boost control A status, noting whether the fault is constant or occurs only under particular conditions.
- Inspect the A module connector, grounds, and harness for looseness, corrosion, heat damage, or chafing.
- Check the A module's supply voltage and ground under the conditions in the manufacturer's diagnostic procedure, since low or unstable power can impair operation.
- If power and wiring are sound, check the vehicle maker's service information for applicable software updates and module tests before considering replacement.
Common fixes
- Clean and secure the boost control A module connector and ground connections.
- Repair damaged wiring or restore the module's specified power supply.
- Install an applicable manufacturer software update or reflash.
- Replace the boost control A module if it fails the specified tests.
Can I keep driving?
A boost control fault can reduce engine power or trigger limp mode, so avoid hard acceleration, towing, and high-speed driving. If power drops sharply or the vehicle cannot maintain a safe speed, stop somewhere safe and arrange assistance.
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.