P258C
Vacuum Pump Control Circuit A Low
Vacuum / brake assist
Generic OBD-II
Medium
What it means
P258C means the PCM detected low voltage (usually a short to ground) in the control circuit for vacuum pump A. On many modern engines this electric pump supplies vacuum for the brake booster, so the main concern is that the pump may not run when needed. It is an electrical fault, not an engine-running problem, and will not stop the car from starting.
Medium
Can I keep driving? Usually drivable, but if this pump feeds the brake booster the pedal can go hard — treat firm/heavy braking as a reason to stop driving.
Common symptoms
What you'll notice
- Check-engine light on
- Firmer, heavier brake pedal if the pump serves the brake booster
- Audible pump running constantly or not at all
- No obvious symptoms in some cases (electrical fault only)
Common causes
Most likely first
- Short to ground or low voltage in the pump's control wiringLikely
- Failed or seized electric vacuum pumpCommon
- Corroded or loose connector at the pump or PCMCommon
- Blown fuse or bad relay feeding the pump circuitLess often
- Faulty PCM driver (least likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the code is current, not historical.
- Inspect the vacuum pump connector and wiring for corrosion, chafing, or a short to ground.
- Check the pump's fuse and relay; verify supply voltage and ground.
- Measure the pump's resistance and command it with a scan tool to see if it runs.
- Replace the pump if it fails to run with good power and ground; otherwise repair the wiring. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P258C?+
Short trips are usually fine, but if the pump supports the brake booster you may notice a harder pedal and longer stopping. Get it checked promptly and brake gently until then.
Can I just clear P258C?+
It will come back until the circuit or pump is repaired. Clearing only resets the light, not the underlying electrical fault.
Related codes
Often seen with P258C
Read & clear P258C yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX