What Does P258C Mean?
The vacuum pump control circuit voltage is below the acceptable threshold. The PCM detects a short to ground or excessive resistance in the vacuum pump control circuit.
Safety Warning
Loss of power brake assist creates dangerous driving conditions with hard pedal and extended stopping distances. Immediate repair required before operating vehicle.
Common Causes
30%
Shorted vacuum pump motor windings
28%
Damaged wiring harness shorted to ground
20%
Corroded or shorted connector terminals
12%
Failed PCM vacuum pump driver (internal short)
10%
Seized vacuum pump causing excessive current draw
Diagnostic Steps
1
Step 1: Disconnect vacuum pump connector and check for short to ground in pump motor windings
2
Step 2: Inspect wiring harness for damage, especially near heat sources or moving components
3
Step 3: Measure current draw of vacuum pump during operation (if pump runs)
4
Step 4: Check for voltage drop in power and ground circuits at pump connector
5
Step 5: Test PCM control signal at pump connector for proper switching operation
Estimated Repair Cost
$200 - $950
Parts + labor, varies by vehicle and location
The vacuum pump control circuit voltage is below the acceptable threshold. The PCM detects a short to ground or excessive resistance in the vacuum pump control circuit.
The most common cause of P258C (Vacuum Pump Control Circuit Low) is: Shorted vacuum pump motor windings
Typical repair costs for P258C range from $200 to $950, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of power brake assist creates dangerous driving conditions with hard pedal and extended stopping distances. Immediate repair required before operating vehicle.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P258C to identify the root cause.
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Quick Info
Category
Powertrain
System
Vacuum System / Brake Assist
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
