P0231
Stop drivingFuel Pump Secondary Circuit Low
Code P0231 means your fuel pump's secondary circuit has low voltage. Common causes: Fuel pump relay (40%), wiring issues (30%), fuel pump module (20%). Drivability: No, stop driving. Repair cost: $30-$500 DIY, $150-$1000 professional.
Can I Drive With P0231?
No, stop driving
Immediate repair needed
Stop driving immediately if: Engine does not start, engine stalls, or significant power loss occurs.
Symptoms of P0231
- 1Engine will not start
- 2Engine cranks but does not fire
- 3Engine stalls unexpectedly while driving
- 4Loss of engine power
- 5Check Engine Light is on
Common Causes of P0231
Parts most likely causing this code, ranked by probability
A faulty fuel pump relay fails to send proper voltage to the fuel pump, resulting in a low circuit condition.
40% of P0231 cases are fixed by replacing this part
Corroded, damaged, or open wiring in the fuel pump's secondary circuit prevents adequate voltage from reaching the pump.
30% of P0231 cases are fixed by repairing this part
A malfunctioning FPDM cannot properly regulate or supply voltage to the fuel pump, leading to a low circuit reading.
20% of P0231 cases are fixed by replacing this part
An internal fault or high resistance within the fuel pump itself can draw too much current or prevent proper voltage flow, triggering a low circuit code.
5% of P0231 cases are fixed by replacing this part
A rare PCM failure can result in incorrect voltage commands or monitoring, falsely or genuinely indicating a low fuel pump circuit.
5% of P0231 cases are fixed by replacing this part
Check These First (Before Buying Parts)
- Check all fuses related to the fuel pump and fuel system in both the underhood and interior fuse boxes.
- Listen for the fuel pump to hum for 1-2 seconds when you turn the key to the 'ON' position (engine off). No hum indicates a power issue or dead pump.
- Swap the fuel pump relay with a known good relay from a non-critical system (like the horn or A/C clutch) to see if the issue resolves.
How to Diagnose P0231
- 1Check all fuses related to the fuel pump and fuel system.
- 2Listen for the fuel pump to prime (a brief hum from the rear of the vehicle) when the key is turned to the 'ON' position.
- 3Locate and swap the fuel pump relay with a known good relay (e.g., from the horn or another non-critical system).
- 4Use a multimeter to test for proper voltage at the fuel pump connector.
- 5Inspect the fuel pump wiring harness for any signs of corrosion, fraying, or damage.
- 6Test the Fuel Pump Driver Module (if equipped) for proper operation and voltage output.
P0231 on Popular Vehicles
Ford F-150
2004-2014The Fuel Pump Driver Module (FPDM) mounted on the frame rail is prone to corrosion and failure due to its exposed location, commonly leading to P0231.
35% fixed by FPDM replacement
Chevrolet Silverado
22007-2013Wiring harness corrosion or issues with the fuel pump control module (if equipped) are common culprits for P0231 in these trucks.
25% fixed by wiring/module repair
Toyota Camry
2007-2017While less common than on trucks, P0231 can occur due to a faulty fuel pump relay or a corroded electrical connection at the fuel pump itself.
20% fixed by relay/connector repair
Frequently Asked Questions
What does P0231 mean?
P0231 indicates a low voltage condition in the secondary circuit that powers your fuel pump. This means the fuel pump is not receiving enough electrical power to operate correctly.
Can I drive with P0231?
No, stop driving. Your engine will likely not start or will stall unexpectedly, leaving you stranded. Driving with this code risks immediate vehicle breakdown.
Will P0231 clear itself?
No, P0231 will not clear itself. This code points to a hard electrical fault that requires diagnosis and repair. The underlying issue must be fixed for the code to clear.
How do I fix P0231 myself?
Start by checking fuel pump fuses and swapping the fuel pump relay with a known good one. Then, use a multimeter to test for voltage at the fuel pump connector and check the wiring harness for continuity and damage.
How much does it cost to fix P0231?
DIY costs range from $30 for a new relay to $500 for a fuel pump driver module or wiring repair. Professional repair costs are $150-$1000, including diagnosis, parts, and labor.
P0231 keeps coming back - why?
The underlying electrical issue was not fully resolved. This often means a faulty wire was missed during inspection, a new relay or module failed prematurely, or the actual fuel pump has an intermittent internal fault.
Will P0231 fail emissions/smog test?
Yes, P0231 will cause your vehicle to fail an emissions or smog test. The illuminated check engine light indicates an active fault that prevents passing inspection.
What's the difference between P0231 and P0230?
P0231 specifically indicates low voltage in the *secondary* fuel pump circuit, which is the power supply to the pump. P0230 indicates a general malfunction in the *primary* fuel pump circuit, which could be an open, short, or other fault in the control side.
P0231 on Ford F-150?
Ford F-150s, especially 2004-2014 models, are known for issues with the Fuel Pump Driver Module (FPDM) located on the frame rail. Corrosion on the FPDM or its mounting can cause P0231.
Questions to Ask Your Mechanic
Did you check the fuel pump relay and its circuit for proper voltage and resistance?
Good answer: Yes, I tested the relay and confirmed it's switching correctly. I also checked the voltage at the relay socket and found it to be within specifications.
What did you find when inspecting the fuel pump wiring harness for damage or corrosion?
Good answer: I performed a visual inspection and continuity test on the entire fuel pump circuit from the relay to the pump. I found some corrosion at connector X, which I cleaned and repaired.
Repair Cost Estimate
DIY Repair
Parts only
$30-$500
Shop Repair
Parts + labor
$150-$1000
Save $120-$500 by doing it yourself
Difficulty
intermediate
Time
1-3 hours
Intermediate - requires electrical diagnostic skills and a multimeter to accurately pinpoint the fault.
Cost of Waiting
Ignoring P0231 means your vehicle will not start or will stall unexpectedly, leaving you stranded. This can lead to towing costs ($100-$300) and potential safety hazards if the engine dies in traffic.
Tools You'll Need
- OBD-II scan tool
- Multimeter
- Test light
- Basic hand tools (screwdrivers, wrenches)
- Wiring diagrams (vehicle-specific)
P0231 is an electrical issue with your fuel pump circuit. Most repairs are straightforward and get your vehicle running reliably again, preventing unexpected breakdowns.
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Your Next Steps
Step 1: Check all relevant fuses and swap the fuel pump relay. If the vehicle starts, replace the relay.
Step 2: If the relay swap does not fix it, use a multimeter to test for voltage at the fuel pump connector. If voltage is low or absent, inspect the wiring harness for damage or corrosion.
Step 3: If wiring is good and voltage is still low, test the Fuel Pump Driver Module (if equipped). If it's faulty, replace it.