What Does P258D Mean?
The PCM has detected an abnormally high voltage in the vacuum pump control circuit. This code is typically found in diesel engines or vehicles with brake booster vacuum pumps, indicating the control circuit voltage exceeds manufacturer specifications.
Common Causes
35%
Shorted vacuum pump control circuit or wiring harness short to power
30%
Failed vacuum pump control module or relay stuck closed
25%
Defective vacuum pump with internal short circuit
10%
PCM internal driver circuit failure
Diagnostic Steps
1
Step 1: Disconnect vacuum pump connector and measure voltage at control circuit terminal with key on - should read battery voltage initially then drop to near zero
2
Step 2: Check for short to power in wiring harness between PCM and vacuum pump using multimeter in resistance mode
3
Step 3: Test vacuum pump control relay operation and inspect relay contacts for welding or damage
4
Step 4: Perform voltage drop test on ground circuit while pump is commanded on
5
Step 5: If all circuits test normal, suspect PCM driver circuit failure and consider module replacement
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The PCM has detected an abnormally high voltage in the vacuum pump control circuit. This code is typically found in diesel engines or vehicles with brake booster vacuum pumps, indicating the control circuit voltage exceeds manufacturer specifications.
The most common cause of P258D (Vacuum Pump Control Circuit High) is: Shorted vacuum pump control circuit or wiring harness short to power
Typical repair costs for P258D range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Reduced brake assist available, requiring increased pedal effort. Vehicle may be difficult to stop in emergency situations, especially for drivers with reduced physical strength.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P258D to identify the root cause.
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Quick Info
Category
Powertrain
System
Brake Vacuum System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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