P258C code meaning
Vacuum Pump Control Circuit A Low
Powertrain system Generic code P25xx codes Check engine light
What P258C means
P258C reports that control circuit A of the electrically driven vacuum pump reads too low, typically because the control or relay line is shorted to ground, the relay coil is faulty, or a blown supply fuse leaves the monitoring line without voltage. Depending on how the circuit is laid out, the pump may then run nonstop or not at all. No manufacturer publishes P258C itself. Ford's hybrid OBD summary shows the kind of window used on this circuit for P258A and P258B: the monitoring voltage should stay between 1.3 and 5.0 V with the relay off and must not drop below 250 mV with it on. CARB 13 CCR 1968.2 treats such electrical outputs as comprehensive components. P258A is the open circuit, P258D the high side; if braking assist suffers, P050F for low brake vacuum can follow.
P258C at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P258C
- Engine or brake warning lamp on
- Pump silent or running constantly
- Firmer brake pedal
Common causes of P258C
- Most likelyControl or relay wire shorted to ground
- PossibleBlown vacuum pump fuse
- PossibleFaulty pump relay or relay coil
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Vacuum pumpWiring harness
What each part of P258C means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 8C | The exact fault in that area. |
What to do next
- Note P258C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P258C
What does P258C mean?
P258C means "Vacuum Pump Control Circuit A Low". P258C reports that control circuit A of the electrically driven vacuum pump reads too low, typically because the control or relay line is shorted to ground, the relay coil is faulty, or a blown supply fuse leaves the monitoring line without voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P258C?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P258C fail an emissions test?
Yes, it can. P258C is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P258C to fix?
Difficulty: medium. A typical repair takes 0.3 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P258C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.