P258B
Vacuum Pump Control Circuit A Range/Performance
Vacuum pump (brake/emissions assist)
Generic OBD-II
Medium
What it means
P258B means the vacuum pump control circuit 'A' isn't performing as the computer expects. Many vehicles use this pump to supply vacuum for brake assist (and some emissions functions), so a fault can make the brake pedal feel firm and increase stopping effort. It usually traces to the pump, its control wiring, or the vacuum plumbing.
Medium
Can I keep driving? Drive with care — if this vacuum pump supplies brake assist, the pedal can feel hard and braking effort increases, so have it checked promptly.
Common symptoms
What you'll notice
- Check-engine light on
- Firmer brake pedal or more effort to stop (on vacuum-assisted brakes)
- Vacuum-operated systems working inconsistently
- Sometimes no obvious symptom beyond the warning light
Common causes
Most likely first
- Faulty vacuum pump or its control circuitLikely
- Open, shorted, or high-resistance wiring in the pump control circuitCommon
- Corroded or loose pump/connector contactsCommon
- Faulty control relay or driver in the moduleLess often
- Blocked, leaking, or collapsed vacuum lines affecting performance feedbackLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and command the vacuum pump with a scan tool to watch its response.
- Inspect the pump control wiring, connector, and any relay for opens, shorts, or corrosion.
- Check the vacuum lines and check valves for leaks or blockage.
- Verify the pump gets power and ground when commanded on.
- Repair the circuit or replace the vacuum pump as indicated, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P258B?+
Be cautious — if the pump assists the brakes, stopping can take more effort. Have it inspected promptly and allow extra braking distance.
Can I just clear P258B?+
It returns until the pump or its control circuit is repaired. Clearing only turns the light off temporarily.
Related codes
Often seen with P258B
Read & clear P258B 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