What Does P1239 Mean?
DTC P1239 indicates a fault in the positive feed (B+) wire to the speed-controlled fuel pump. The PCM or FPDM has detected that the main power supply to the fuel pump is not within expected parameters, either showing insufficient voltage, an open circuit, or excessive resistance on the supply side. This directly affects the pump's ability to generate proper fuel pressure.
Safety Warning
A compromised positive feed to the fuel pump can cause intermittent or complete loss of fuel delivery. This can result in engine stalling without warning, particularly dangerous at highway speeds or in traffic.
Common Causes
30%
Corroded or damaged fuel pump positive feed wire or connector
25%
Fuel pump relay with high contact resistance or intermittent operation
15%
Blown or degraded fuel pump fuse with partial contact
15%
Poor battery or alternator voltage causing low system voltage
15%
FPDM power input circuit fault
Diagnostic Steps
1
Check the fuel pump fuse for integrity — even if it looks good, measure resistance across it to ensure low resistance.
2
Measure battery voltage at the fuel pump relay output with the relay energized — should be within 0.5V of battery voltage.
3
Perform a voltage drop test from the battery positive terminal to the fuel pump positive wire at the tank — total drop should be less than 1.0V with the pump running.
4
Inspect the fuel pump relay contacts by swapping with an identical relay from another circuit and clearing codes.
5
Check the FPDM power input pins for proper voltage with the ignition on and pump commanded to run.
Estimated Repair Cost
$50 - $500
Parts + labor, varies by vehicle and location
DTC P1239 indicates a fault in the positive feed (B+) wire to the speed-controlled fuel pump. The PCM or FPDM has detected that the main power supply to the fuel pump is not within expected parameters, either showing insufficient voltage, an open circuit, or excessive resistance on the supply side. ...
The most common cause of P1239 (Speed Fuel Pump Positive Feed Fault) is: Corroded or damaged fuel pump positive feed wire or connector
Typical repair costs for P1239 range from $50 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A compromised positive feed to the fuel pump can cause intermittent or complete loss of fuel delivery. This can result in engine stalling without warning, particularly dangerous at highway speeds or in traffic.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1239 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Delivery
Difficulty
Type
Manufacturer
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