OBD-II code · Powertrain (generic, extended)
P25AF Coolant Temperature Control Module Requested MIL Illumination
A dedicated coolant-temperature control module (used on engines with electric coolant pumps and electronic thermostats to keep the cylinder head and block at independent setpoints) has requested the ECM to illuminate the MIL because of an emissions-relevant fault on its side. Original fault is in that module.
Is it safe to drive with P25AF?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyInternal fault — read the module DTCs
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–4 h
- Emissions test
- Likely to fail
- Parts involved
- Coolant Temp Control Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.