P25AF: Coolant Temperature Control Module Requested MIL Illumination
Standardized SAE J2012 code · P25xx — Auxiliary inputs
What does P25AF mean?
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.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Common causes
- High Internal fault — read the module DTCs
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P25AF on the same make and model first.
P25AF in the community
Ask about P25AFNo one has posted about P25AF yet
Share your vehicle, the tool you used and what you tested — the first thread helps everyone who searches for this code.
Describe your P25AF problem