What it means
The control module monitors whether exhaust heat exchanger bypass valve B can close when commanded. It sets this code when the valve remains open or its position feedback indicates that it has not closed.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bypass valve B controls whether exhaust passes through the exhaust heat exchanger or around it. The module checks whether valve B closes when commanded and sets P23A6 if it remains open or its position feedback does not confirm closure.
Common causes
Most likely first.
- Valve stuck open
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
Symptoms
- Check-engine light on
- Exhaust heat exchanger may not bypass as commanded
- Possible change in exhaust heat management
How to diagnose it
- Record freeze-frame data and check live data for valve B's close command and position feedback when the fault is present.
- With the exhaust cool, inspect valve B's linkage and surrounding area for deposits, debris, or mechanical damage that could hold it open.
- Check the valve B connector and position-sensor wiring for loose or corroded terminals that could falsely report an open valve.
- If supported, command valve B closed with a scan tool and observe whether it moves and whether feedback changes.
- If the valve cannot close, check for binding, wear, or actuator failure using the manufacturer's procedure.
Common fixes
- Remove debris or deposits preventing valve B from closing, if permitted by the service procedure.
- Repair a loose or damaged valve B linkage.
- Repair corroded connectors or damaged position-sensor wiring.
- Replace a faulty actuator or position sensor if tests confirm the fault.
- Replace bypass valve B if it remains mechanically stuck open.
Can I keep driving?
If the vehicle runs normally, drive only as needed to arrange diagnosis and avoid heavy loads because valve B may not manage exhaust heat as intended. Stop if performance changes or the exhaust system shows signs of overheating.
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.