What it means
The exhaust flow control valve B reports a control circuit/open 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 is an actuator that changes exhaust routing for back-pressure or noise control. The module monitors its control circuit, and this code means the circuit is open, such as from a broken control wire, an open actuator coil, or a terminal pushed back in the connector.
Common causes
Most likely first.
- Open in actuator control wire
- Open actuator coil
- Pin pushed back out of connector body
Symptoms
- Check-engine light
- Reduced engine power
- Poor acceleration
How to diagnose it
- Read freeze-frame data and check for related exhaust-valve codes to see when valve B’s control circuit fault was detected.
- With the exhaust cool, inspect valve B’s actuator connector for a pushed-back pin, loose latch, corrosion, or heat-damaged wiring.
- Trace valve B’s control wire and check for an open or break using the wiring diagram.
- Measure actuator-coil continuity and circuit continuity against the manufacturer’s specification.
- If the harness and connector are intact, test valve B’s actuator and replace it if its coil is open.
Common fixes
- Seat the pushed-back valve B connector pin and secure the connector.
- Repair an open or broken valve B control wire.
- Replace damaged connector terminals or wiring.
- Replace valve B’s actuator if its coil is open.
Can I keep driving?
If the engine runs smoothly and power is normal, a short, gentle drive may be possible. Avoid hard acceleration and do not rely on full power, since valve B may not move as commanded and the control module may limit engine output.
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.