What it means
The turbocharger or supercharger boost control A circuit is intermittent or erratic.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Boost control A is the circuit and actuator mechanism that helps regulate turbocharger or supercharger boost. The computer sets this code when control A's signal or operation becomes intermittent or erratic, such as when a loose connection briefly loses contact.
Common causes
Most likely first.
- Connector loose or corroded
- Wiring chafed inside loom
- Connector with intermittent contact under vibration
Symptoms
- Check engine light on
- Reduced engine performance
How to diagnose it
- Read freeze-frame data and review control A, commanded boost, and actual boost readings for changes around the fault.
- Inspect the control A connector for looseness, corrosion, or terminals that may move under vibration.
- Follow the control A harness through its loom and look for chafing, heat damage, or a section pulled tight.
- With a scan tool, monitor control A feedback while gently moving the harness and connector to identify an intermittent signal.
- Test the control A circuit and actuator against the manufacturer's specification, including checks for intermittent opens or shorts.
Common fixes
- Reseat and secure a loose control A connector.
- Clean or repair corroded connector terminals.
- Repair chafed control A wiring and secure it against vibration.
- Replace a control A actuator only if it fails testing after wiring faults are ruled out.
Can I keep driving?
You may be able to drive gently if power remains normal, but avoid hard acceleration and heavy loads because the fault can recur and reduce boost unexpectedly. Stop if the loss of power makes the vehicle difficult to control in traffic.
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.