OBD-II code · Powertrain (generic)
P026F Coolant Thermostat Performance
Thermostat does not regulate coolant temperature in the expected range. Often stuck open (slow warmup) or stuck closed (overheat).
Is it safe to drive with P026F?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyThermostat stuck
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Thermostat
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.