P0231: Fuel Pump Secondary Circuit Low
Can you still drive? Not recommended. A failing fuel pump can leave you stranded if it stops working completely. Tow to a repair shop if possible.
What Does P0231 Mean?
Code P0231 indicates that the voltage in the fuel pump secondary circuit is below the expected level. This circuit provides the actual power to run the fuel pump, and low voltage typically means the pump is drawing excessive current due to wear, or there is a problem in the power supply circuit including the relay, wiring, or ground.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Worn fuel pump motor drawing excessive current
- Corroded fuel pump wiring or ground connection
- Failing fuel pump relay
- High resistance in the fuel pump circuit
- Clogged fuel filter causing pump strain
Symptoms
- Check engine light on
- Engine stalling or sputtering
- Loss of power during acceleration
- Hard starting
- Engine dies at idle
Diagnostic Steps
- 1Read freeze frame data and note fuel pressure if available
- 2Check fuel pump relay operation and swap with a known good relay
- 3Test voltage at the fuel pump connector with the pump running
- 4Measure fuel pump current draw and compare to specifications
- 5Check the ground connection at the fuel pump for corrosion
- 6Inspect wiring harness for damage or high resistance connections
Recommended Parts & Tools
fuel pump assembly
fuel pump relay
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $200 - $900 |
Get a Personalized AI Diagnostic Report
Get a detailed AI diagnosis for code P0231 specific to your vehicle. Includes step-by-step repair instructions, exact parts needed, and a cost breakdown tailored to your make and model.
Chat with AI About P0231Commonly Affected Vehicles
Related Recalls
1 Active Recall — 2026 Ford F-150
The following NHTSA safety recalls have been issued for this vehicle. Contact your dealer to check if your vehicle is affected.
ELECTRICAL SYSTEM: INTEGRATED TRAILER BRAKE CONTROL
Ford Motor Company (Ford) is recalling certain 2021-2026 F-150, 2022-2026 F-250 SD, F-350 SD, F-450 SD, F-550 SD, Maverick, 2024-2026 Ranger, 2023-2026 F-600 SD, 2022-2027 Lincoln Navigator, Expedition, and 2026 E-Transit vehicles. When towing a trailer, the integrated trailer module (ITRM) may lose communication with the vehicle, possibly causing a loss of brake and turn signal lights, or a loss of brake function. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 108, " Lamps, Reflective Devices, and Associated Equipment."
Remedy: The integrated trailer module software will be updated by a dealer, or through an over-the-air (OTA) update, free of charge. Owner notification letters are expected to be mailed March 17, 2026. Owners may contact Ford customer service at 1-866-436-7332. Ford's number for this recall is 26C10. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning March 17, 2026.
Data provided by the National Highway Traffic Safety Administration (NHTSA).
Frequently Asked Questions
Can a bad relay cause P0231?
Yes, a failing fuel pump relay can cause low voltage in the secondary circuit. Swapping the relay with an identical one from another circuit is a quick and free diagnostic test.
How do I know if my fuel pump is dying?
Common signs include whining noise from the fuel tank, difficulty starting, loss of power at high speeds, and engine sputtering. Measuring fuel pump current draw can confirm if the pump motor is worn.
Community Fix Reports
Community reports are user-submitted and not verified by Auto AI Buddy. Results may vary.
Related Codes
Affiliate Disclosure: This page contains affiliate links. If you purchase products through these links, we may earn a small commission at no additional cost to you. This helps us maintain this free resource. We only recommend products we believe will help you diagnose and repair your vehicle. Prices shown are estimates and may vary.