P26B1: Engine Coolant Bypass Valve A Stuck Closed
Standardized SAE J2012 code · P26xx — Computer and output circuits
What does P26B1 mean?
The coolant bypass valve A is stuck closed. Coolant cannot bypass the radiator during warm-up so warm-up takes longer and emissions in the warm-up phase rise.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Common causes
- High Valve seized closed by debris
- Medium Actuator linkage jammed in closed position
- Low Carbon or debris buildup preventing free movement
Likelihood is a general estimate across vehicles; your make and model may differ.
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P26B1 in the community
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