Faulty fuel volume regulator or metering valve (internal short or open winding); Damaged wiring to the regulator, such as chafing causing a short to earth or an open circuit; Corroded, loose or contaminated connector at the regulator or control unit; Low fuel supply pressure from the lift pump or a blocked fuel filter affecting regulator operation; Low or unstable system voltage or poor earth connections; Fault inside the engine control unit driver circuit.

P0003

Fuel Volume Regulator A Control Circuit Low.

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
03: FaultThe specific fault in that area

What it means

P0003 is the generic code for a low signal in the control circuit of fuel volume regulator A. The engine control unit commands the regulator, which meters fuel to the high pressure pump, and it has seen the circuit voltage or current lower than expected. This points to an electrical fault such as a short to earth or an open circuit, or a fault in the regulator itself.

Symptoms

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

Possible causes

Faulty fuel volume regulator or metering valve (internal short or open winding)likely
Damaged wiring to the regulator, such as chafing causing a short to earth or an open circuitlikely
Corroded, loose or contaminated connector at the regulator or control unitlikely
Low fuel supply pressure from the lift pump or a blocked fuel filter affecting regulator operationpossible
Low or unstable system voltage or poor earth connectionspossible
Fault inside the engine control unit driver circuitrare

How to diagnose

Read all stored and pending codes and note freeze frame data, including engine speed, load and rail pressure where available
Check for related codes covering fuel rail pressure, battery voltage or sensor supply faults, and deal with those first
Visually inspect the regulator wiring and connector for chafing, heat damage, fluid ingress, corrosion and bent or pushed-out pins
Check battery condition, charging voltage and the relevant earth connections
Measure the regulator coil resistance and compare with the manufacturer specification for that engine
Check the wiring between regulator and control unit for continuity and for shorts to earth and to supply, with the connectors disconnected
With a suitable scan tool, command the regulator if the vehicle supports it and watch the commanded and actual fuel pressure
Check lift pump pressure and fuel filter condition, following the procedure for the specific model and engine

How to fix

Replace the fuel volume regulator or metering unit if its resistance or operation is out of specification
Repair or replace damaged wiring and secure it clear of heat and abrasion
Clean or replace corroded or damaged connectors and terminals
Replace a blocked fuel filter and repair any lift pump fault found
Correct battery, charging or earth faults
Have the control unit tested and repaired or replaced only after wiring and regulator are proven good

Can I keep driving?

Medium severity

Short, careful driving may be possible, but the engine may run poorly, enter limp mode or stall. Have it checked soon, as fuel system faults can leave you stranded or worsen.

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