OBD-II code · Powertrain (generic, extended)
P26AB Engine Coolant Bypass Valve A Stuck/Open
The coolant bypass valve A is stuck in the open position. Coolant always bypasses the radiator, leading to overheating under load.
Is it safe to drive with P26AB?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyValve seized open by sediment or wax
- PossibleBroken return spring
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Coolant Bypass Valve A, Thermostat Housing
Related codes
- P26AFEngine Coolant Bypass Valve B Stuck/Open
- P26BAEngine Coolant Bypass Valve C Stuck/Open
- P26C0Engine Coolant Bypass Valve D Stuck/Open
- P2E65Engine Coolant Bypass Valve E Stuck/Open
- P26A8Engine Coolant Bypass Valve A Position Sensor Circuit Intermittent/Erratic
- P26A9Engine Coolant Bypass Valve A Position Sensor Stop/Minimum Stop Performance
- P26AAEngine Coolant Bypass Valve A Position Sensor Maximum Stop Performance
- P26ACEngine Coolant Bypass Valve B Control Circuit / Open
- P26ADEngine Coolant Bypass Valve B Control Circuit Low
- P26AEEngine Coolant Bypass Valve B Control Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.