What it means
Exhaust Heat Exchanger Bypass Valve B Control Circuit Open: the control circuit is open. Likely a broken wire, disconnected connector, or failed actuator.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Exhaust heat exchanger bypass valve B directs exhaust around the heat exchanger when the control module requests a bypass. The module monitors the valve's control circuit; this code sets when that circuit is open, so the actuator may not receive the command needed to move valve B.
Common causes
Most likely first.
- Open in harness or actuator
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check-engine light on
- Exhaust heat exchanger may not bypass as commanded
- Possible change in exhaust heat management
How to diagnose it
- Check freeze-frame data and available commanded-versus-actual data to confirm the fault involves the B bypass valve circuit.
- With the exhaust cool, inspect the B valve actuator connector and harness for disconnection, heat damage, broken wires, or pushed-back pins.
- Use the wiring diagram to check continuity through the B valve control circuit and look for an open between the actuator and module.
- Check connector terminal fit and the actuator winding or internal circuit against the manufacturer's specification.
- If the wiring and actuator test correctly, inspect the control module connection and its circuit for an open before considering module failure.
Common fixes
- Reconnect a loose B bypass valve connector and secure its harness.
- Repair a broken or heat-damaged wire in the B valve control circuit.
- Replace pushed-back or damaged connector terminals.
- Replace the B bypass valve actuator if its internal circuit is open.
- Repair the module-side connection if testing identifies an open there.
Can I keep driving?
If the engine runs normally, a short trip is usually possible, but avoid heavy loads if exhaust heat management appears abnormal. Arrange repair soon, and stop if warning signs of overheating or unusual exhaust heat occur.
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.