🔧 Code Definition

P0001 – Fuel Volume Regulator Control Circuit/Open

This code means the Engine Control Module (ECM) has detected an open circuit (disconnection or high resistance) in the fuel volume regulator control circuit.

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🧩 System Involved

The Fuel Volume Regulator (FVR) or Fuel Metering Unit (FMU) is typically mounted on the high-pressure fuel pump.

Its job is to control the amount of fuel entering the pump, ensuring the correct pressure for fuel injection.

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⚠️ Possible Symptoms

Engine won’t start or has difficulty starting

Rough idle or stalling

Poor acceleration or lack of power

Check Engine Light (MIL) ON

Possible fuel economy drop

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🛠️ Common Causes

1. Open circuit in the fuel volume regulator wiring harness

2. Faulty fuel volume regulator (FVR) / metering valve

3. Corroded or damaged electrical connectors

4. Blown fuse or faulty relay related to the fuel system

5. ECM fault (less common)

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🔍 Diagnosis & Repair Steps

1. Visual inspection

Check wiring from ECM to fuel volume regulator for damage or disconnection.

Inspect connectors for corrosion or loose pins.

2. Check voltage supply

Use a multimeter: there should be a proper voltage and ground at the regulator connector.

3. Test the FVR

Measure resistance of the regulator coil (compare to manufacturer specs).

If open/infinite resistance → regulator is bad.

4. Check for fuel contamination

Dirty fuel or water can cause the regulator to stick.

5. If wiring and FVR are OK → suspect ECM (rare).