Damaged, chafed or broken wiring in the regulator control circuit (open circuit); Corroded, loose or pushed-out pins in the regulator connector; Faulty fuel volume regulator or fuel metering valve (open coil); Fault in the fuel pump or pressure regulation assembly that houses the regulator; Low or unstable supply voltage or poor earth to the regulator circuit; Fault inside the engine control unit driver circuit; Outdated control unit software where the manufacturer has issued a known update for this fault.

P0001

Fuel Volume Regulator A Control Circuit/Open.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
0: AreaFuel and air metering, auxiliary emission controls
01: FaultThe specific fault in that area

What it means

P0001 is the generic code for an open or faulty control circuit for fuel volume regulator A. The engine control unit commands the regulator, which meters how much fuel the high pressure pump delivers or returns, and it has detected an open circuit or a fault in that control circuit. The exact regulator design and location depend on the engine and fuel system.

Symptoms

Engine warning light on
Hard starting or long cranking
Rough idle or hesitation under load
Loss of power or limp mode
Engine stalling or surging
Poor fuel economy

Possible causes

Damaged, chafed or broken wiring in the regulator control circuit (open circuit)likely
Corroded, loose or pushed-out pins in the regulator connectorlikely
Faulty fuel volume regulator or fuel metering valve (open coil)likely
Fault in the fuel pump or pressure regulation assembly that houses the regulatorpossible
Low or unstable supply voltage or poor earth to the regulator circuitpossible
Fault inside the engine control unit driver circuitrare
Outdated control unit software where the manufacturer has issued a known update for this faultrare

How to diagnose

Read all stored and pending codes and note any related fuel pressure or rail pressure codes
Review freeze frame data to see engine speed, load and temperature when the code set
Visually inspect the regulator, its connector and the wiring for damage, rubbing, heat damage, corrosion or fluid contamination
Check the connector pins for tension, security and corrosion
Check the fuel pressure or rail pressure against specification using live data, comparing the commanded and actual values
Measure the regulator coil resistance and compare it with the manufacturer's specification for that engine
With the circuit disconnected, test the control wires for continuity, short to earth and short to supply, and check the supply voltage and earth
Check for technical service bulletins or software updates for the model and engine

How to fix

Repair or replace damaged wiring and restore the circuit continuity
Clean, repair or replace the regulator connector and terminals
Replace the fuel volume regulator or the pump assembly if the regulator is not serviced separately and tests faulty
Restore a good supply and earth connection to the circuit
Update the control unit software only if a known update covers this fault, and replace the control unit if its driver circuit is proven faulty

Can I keep driving?

Medium severity

The car may run in a reduced power mode or stall, so avoid long journeys and get it checked soon. Stop driving if it cuts out or loses power, as this can be unsafe in traffic.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.