Fuel Pump Secondary Circuit Low Voltage
The P0231 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the fuel pump secondary circuit, which powers the fuel pump relay or the fuel pump itself. This can be caused by a faulty fuel pump relay, a blown fuse, damaged wiring or connectors, a failing fuel pump, or a defective PCM. The low voltage prevents the fuel pump from operating at full capacity, leading to insufficient fuel pressure.
01. Most Common Causes
- Blown fuel pump fuse
- Faulty fuel pump relay
- Damaged wiring or connectors in the fuel pump circuit
- Failing fuel pump motor
- Corroded ground connections
02. Symptoms You Will Notice
- Engine cranks but does not start
- Loss of power or hesitation during acceleration
- Engine stalling shortly after starting
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for additional codes.
Step 2: Inspect the fuel pump fuse and relay; replace if blown or faulty.
Step 3: Check voltage at the fuel pump connector with a multimeter while the engine is cranking; should be battery voltage.
Step 4: Inspect wiring and connectors for damage, corrosion, or loose connections; repair as needed.
Step 5: If voltage is present and wiring is good, test the fuel pump resistance; replace if out of specification.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may stall unexpectedly or fail to start, posing a safety risk.
How much does it cost to fix?▼
Repair costs vary from $150 to $400, depending on the cause. A fuel pump replacement can be more expensive.