Vacuum Pump Control Circuit High
The P258D code indicates that the powertrain control module (PCM) has detected a high voltage condition in the vacuum pump control circuit. This circuit controls the electric vacuum pump, which provides vacuum for brake boost and other systems. A high voltage reading typically points to a short to power, a faulty pump, or a wiring issue.
01. Most Common Causes
- Short to power in the vacuum pump control circuit
- Faulty vacuum pump relay
- Defective vacuum pump motor
- Damaged wiring or connector
02. Symptoms You Will Notice
- Hard brake pedal (loss of power brake assist)
- Check Engine Light illuminated
- Possible vacuum leak hissing sound
- Reduced engine performance
03. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P258D is present.
Step 2: Visually inspect vacuum pump wiring and connector for damage or corrosion.
Step 3: Test vacuum pump control circuit voltage with a multimeter; compare to manufacturer specs.
Step 4: Check vacuum pump relay operation and replace if faulty.
Step 5: Test vacuum pump motor resistance and replace if out of range.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The code indicates a potential loss of brake assist, which can lead to a hard brake pedal and increased stopping distance. Have the vehicle inspected immediately.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on the root cause. Replacing a vacuum pump can cost more, but simple wiring repairs are cheaper.