What it means
The exhaust flow control valve B reports a control circuit high condition. Exhaust routing for back-pressure or noise control cannot be commanded reliably.
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
Exhaust flow control valve B’s actuator changes exhaust routing to manage back-pressure or noise, and the module monitors the actuator control circuit. This code means the circuit voltage is higher than expected, commonly because the control wire is shorted to battery voltage, the actuator coil is open, or connector contact is poor.
Common causes
Most likely first.
- Control wire shorted to B+
- Open actuator coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Reduced engine power
- Poor acceleration
How to diagnose it
- Use freeze-frame data and related codes to confirm when the valve B control-circuit high condition was recorded.
- With the exhaust cool, inspect valve B’s actuator connector and harness for corrosion, loose pins, or a control wire contacting a power feed.
- Check the control wire for a short to battery voltage and verify the circuit routing against the wiring diagram.
- Measure actuator-coil continuity and circuit behavior against the manufacturer’s specification to identify an open coil or wiring fault.
- If the wiring and connector are sound, test valve B’s actuator and replace it if the coil is open.
Common fixes
- Restore proper contact at valve B’s corroded or loose actuator terminals.
- Repair the control wire if it is shorted to battery voltage.
- Repair damaged wiring or connector pins.
- Replace valve B’s actuator if its coil is open.
Can I keep driving?
If the vehicle runs smoothly and power is normal, keep any necessary drive short and gentle. Avoid hard acceleration because the module may reduce power when valve B cannot be controlled reliably.
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.