P25F1 marks a high reading on the vacuum pump's second (B) control circuit: the module sees voltage on the switched side when it should be low, for example because the line is shorted to battery voltage, the relay contacts have welded together or the pump has lost its ground. In the welded-relay case the pump keeps running after it has been switched off, which wears it out and drains the battery. No manufacturer documents P25F1 publicly. Ford's hybrid summary checks the comparable circuit A against a 1.3 to 5.0 V window with the relay open, a pattern that would also catch a supply that is stuck on. CARB 13 CCR 1968.2 requires electrical outputs to be checked for circuit faults. The opposite fault is P25F0, and P25EE is the open circuit. Drivers may hear the pump running constantly.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Vacuum pump running constantly, even with the vehicle switched off
- Discharged 12 V battery
- Warning lamp on
Most likely causes
- Pump relay contacts welded closed
- Feedback or supply line shorted to battery voltage
- Lost ground connection at the pump
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P25F1 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 5: Speed and idle
- F1: Specific fault in that system
Frequently asked questions
Can I keep driving with code P25F1?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P25F1?
The most common causes are: pump relay contacts welded closed; feedback or supply line shorted to battery voltage; lost ground connection at the pump.
Related codes
- P25EEVacuum Pump Control Circuit B/Open
- P25EFVacuum Pump Control Circuit B Range/Performance
- P25F0Vacuum Pump Control Circuit B Low
- P258DVacuum Pump Control Circuit A High
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.