P0001
Fuel Volume Regulator Control Circuit/OpenP0001 is a generic OBD-II powertrain diagnostic trouble code: Fuel Volume Regulator Control Circuit/Open. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0001 means
P0001 — Fuel Volume Regulator Control Circuit/Open — is set when the Engine Control Module (ECM) detects an open-circuit condition in the wiring or solenoid coil of the Fuel Volume Regulator (FVR), also called the Fuel Volume Control Valve (FVCV). The FVR is a duty-cycle-controlled solenoid mounted on the high-pressure fuel pump (Bosch CP1/CP3/CP4, Denso HP3/HP4, or Delphi DFP3/DFP6) that meters the volume of fuel entering the high-pressure pumping element. On common-rail diesel engines the ECM commands the FVR by switching its ground terminal at a variable duty cycle; the solenoid must see continuity through both its coil and the wiring harness for the control signal to have any effect.
An open circuit — caused by a broken wire, corroded connector, or failed solenoid coil (typically 3–6 Ω internal resistance at room temperature) — prevents the ECM from controlling fuel metering at all. On a normally-open FVR (the most common design), an open control circuit leaves the valve fully open, flooding the high-pressure element and causing excessively high rail pressure. On a normally-closed design, the opposite occurs: rail pressure collapses. Either way the engine will typically not start or will stall under load. The code is also seen on gasoline direct-injection (GDI) engines using a similar high-pressure pump architecture.
P0001 is critical on high-mileage common-rail diesel vehicles — particularly VW/Audi TDI (1.6 TDI/2.0 TDI), Ford/Navistar 6.7 L Power Stroke, and Toyota 1AD/2AD diesels — where pump feed lines and solenoid connectors are exposed to heat cycling and vibration over hundreds of thousands of kilometres.
Common causes
Most-frequently reported root causes when P0001 is logged.
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1
Broken, chafed, or corroded wire in the FVR solenoid control circuit between the ECM and the pump.
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2
Loose, backed-out, or corroded connector at the FVR solenoid on the high-pressure pump.
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3
Failed FVR solenoid coil with an open winding (measure resistance; open or infinite reading confirms failure).
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4
High resistance in the ECM driver circuit output pin due to corrosion inside the ECM connector.
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5
Blown fuse in the FVR power supply circuit (on some Ford/Navistar applications, fuse F74).
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6
Wiring harness routed too close to a heat source causing insulation breakdown and intermittent opens.
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7
ECM internal driver transistor failure preventing any output signal to the FVR.
Symptoms drivers notice
How to diagnose P0001
A typical diagnostic flow when this code is present.
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1
Connect a scan tool and record live fuel rail pressure data; compare commanded vs. actual rail pressure to confirm the FVR is not responding.
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2
Disconnect the FVR solenoid connector and measure solenoid resistance with a multimeter (typically 3–6 Ω at 20 °C); an open reading confirms a failed solenoid.
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3
With the connector still disconnected, back-probe the harness-side terminals and verify battery-level voltage on the supply wire and continuity to ECM ground on the control wire.
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4
Inspect the entire wiring harness from the pump to the ECM for chafing, melted insulation, or broken wires — pay particular attention to areas near the exhaust and engine mounts.
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5
Check and replace any blown fuses in the FVR circuit per the vehicle-specific fuse chart.
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6
If wiring and solenoid test good, perform ECM pin voltage and resistance checks per the workshop manual to rule out an internal ECM driver fault.
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7
After replacing the faulty component, clear codes, perform a road test with live fuel pressure monitoring, and confirm rail pressure follows commanded values.
Vehicles where we've handled P0001
Platforms in our catalogue with confirmed P0001 coverage.
Related powertrain codes
Frequently asked questions
Will the engine start with P0001 active?
Often not. Because the FVR controls how much fuel enters the high-pressure pump, an open circuit leaves fuel metering uncontrolled. On most common-rail diesel applications the engine will crank without starting, or may fire briefly and stall. GDI gasoline engines may start but run very poorly.
Can I drive the vehicle to the workshop with this code?
Not recommended. Uncontrolled rail pressure can damage injectors, the high-pressure pump, and fuel rails. If the engine is running, drive only the minimum distance necessary to reach a repair facility and avoid high-load conditions.
How do I tell if the solenoid or the wiring is at fault?
Disconnect the solenoid connector and measure resistance across the solenoid terminals. A reading in the expected range (typically 3–6 Ω) with an open circuit reading on the harness side points to broken wiring. An open or infinite reading at the solenoid itself confirms solenoid failure.
Is P0001 common on TDI or Power Stroke engines?
Yes. VW/Audi TDI engines (especially 1.6 TDI with Bosch CP4 pump) and Ford 6.7 L Power Stroke are frequently affected. The solenoid connector on the CP4 pump sits close to the engine block and is prone to heat-induced corrosion. On the Power Stroke, fuse F74 in the battery junction box should be checked first.
Disabling P0001 in software
RaceTune can permanently disable P0001 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECUs with a P0001 disable in our catalogue
Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.
- Bosch EDC17C50 verified 1 software version
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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