What Does P1231 Mean?
DTC P1231 indicates the fuel pump secondary circuit is reading low voltage when the high-speed fuel pump command is active. This means the fuel pump driver module (FPDM) is unable to deliver full voltage to the fuel pump during high-demand conditions such as wide-open throttle or heavy load. The engine may experience fuel starvation under high-demand driving scenarios.
Safety Warning
Insufficient fuel pump output at high speed can cause lean misfires, engine hesitation, or stalling during highway driving or hard acceleration. This creates a significant safety hazard, especially when merging or passing.
Common Causes
30%
Failing fuel pump drawing excessive current and causing voltage drop
25%
Corroded or high-resistance fuel pump wiring or connector at the tank
20%
Defective fuel pump driver module (FPDM)
15%
Poor ground connection at the fuel pump or FPDM
10%
Damaged fuel pump relay or fuse with high contact resistance
Diagnostic Steps
1
Use a scan tool to command the fuel pump to high speed and monitor fuel pump duty cycle and secondary circuit voltage at the FPDM.
2
Measure voltage directly at the fuel pump connector at the tank with the pump running at high speed — compare to battery voltage; more than 1.5V drop indicates a wiring or connection issue.
3
Check the fuel pump ground circuit resistance from the pump connector back to the chassis ground point — should be less than 0.5 ohms.
4
Inspect the fuel pump driver module connector for corrosion, spread terminals, or heat damage.
5
Measure fuel pump current draw — a pump drawing more than manufacturer specification (typically >8A) suggests internal pump wear.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
DTC P1231 indicates the fuel pump secondary circuit is reading low voltage when the high-speed fuel pump command is active. This means the fuel pump driver module (FPDM) is unable to deliver full voltage to the fuel pump during high-demand conditions such as wide-open throttle or heavy load. The eng...
The most common cause of P1231 (Fuel Pump Secondary Circuit Low, High Speed) is: Failing fuel pump drawing excessive current and causing voltage drop
Typical repair costs for P1231 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Insufficient fuel pump output at high speed can cause lean misfires, engine hesitation, or stalling during highway driving or hard acceleration. This creates a significant safety hazard, especially when merging or passing.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1231 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Delivery
Difficulty
Type
Manufacturer
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