P25EF says that the B circuit driving the electric vacuum pump is electrically present but its behaviour does not match the command: the feedback on the switched side looks implausible, or the pump runs without the expected effect on brake vacuum. No manufacturer documents P25EF publicly. Ford's hybrid OBD summary shows the type of logic used on the neighbouring circuit A, where P258B combines an out-of-window monitoring voltage with the relay off and a reading under 250 mV with the relay on. FCA's bulletin S1805000006 ties the A-circuit performance code to pumps that cannot hold enough vacuum and has hoses, check valves, fuses and terminals inspected first. A similar approach suits circuit B. CARB requires plausibility monitoring of such outputs. The brake pedal may feel firmer than usual.
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
- Brake pedal firmer than normal
- Vacuum pump running longer or more often
- Warning lamp on
Most likely causes
- Worn vacuum pump that runs but builds too little vacuum
- Leaking vacuum hose or faulty check valve
- Corroded terminals causing an unstable feedback voltage
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 P25EF means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 5: Speed and idle
- EF: Specific fault in that system
Frequently asked questions
Can I keep driving with code P25EF?
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 P25EF?
The most common causes are: worn vacuum pump that runs but builds too little vacuum; leaking vacuum hose or faulty check valve; corroded terminals causing an unstable feedback voltage.
Related codes
- P25EEVacuum Pump Control Circuit B/Open
- P25F0Vacuum Pump Control Circuit B Low
- P25F1Vacuum Pump Control Circuit B High
- P258BVacuum Pump Control Circuit A Range/Performance
- P0556Brake Booster Pressure Sensor Circuit Range/Performance
Sources
- fordservicecontent.com: OBDSM1901 HEV
- static.nhtsa.gov: MC 10173320 9999
- law.cornell.edu: 13 CCR 1968.2
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.