Vacuum Pump Control Range/Performance
The P258B code indicates that the Engine Control Module (ECM) has detected a malfunction in the vacuum pump control circuit, specifically that the pump's performance is outside the expected range. This often relates to the pump not generating sufficient vacuum or the control circuit having an electrical fault. The vacuum pump is critical for brake booster operation and emissions systems, so this code can affect braking performance and engine management.
01. Most Common Causes
- Faulty vacuum pump
- Open or shorted vacuum pump control circuit
- Failed vacuum pump relay or fuse
- ECM software or hardware issue
02. Symptoms You Will Notice
- Hard brake pedal (reduced brake assist)
- Check Engine Light illuminated
- Possible vacuum leak hissing sound
- Engine running rough or stalling
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect vacuum pump, wiring, and connectors for damage.
Step 3: Test vacuum pump operation using a vacuum gauge and multimeter.
Step 4: Check vacuum pump relay and fuse with a test light.
Step 5: If wiring and components are OK, replace the vacuum pump.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vacuum pump assists braking; failure can lead to a hard brake pedal and increased stopping distance. Have it diagnosed immediately.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, including parts (vacuum pump $100-$250) and labor (1-2 hours).