P23A6
Exhaust Heat Exchanger Bypass Valve B Stuck Open
Bypass valve B is stuck in the open position - exhaust bypasses the heat exchanger continuously, slowing engine warm-up.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Valve stuck openCommon
- Carbon or debris buildup preventing free movementLess likely
- Component wear with age - mechanical playLess likely
Parts involved
- Exhaust Bypass Valve B
P23A6 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.