P01F0
Coolant Temperature Relapsed Below Diagnostic Monitoring Temperature
Coolant temperature dropped below the diagnostic monitoring threshold after warm-up. Often thermostat stuck open or stuck-open coolant heater bypass.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Thermostat stuck openCommon
Parts involved
- Thermostat
- Coolant Circuit
P01F0 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.