P0004: Fuel Volume Regulator Control Circuit High

What does P0004 mean?

The computer detects an above-limit measurement in the fuel-volume regulator control circuit. This is not by itself a measurement of excessive fuel pressure. This system is common on common-rail diesels and gasoline direct-injection engines; the exact regulator arrangement varies by engine.

Generic OBD-II definition: Fuel Volume Regulator Control Circuit High. Confirm applicability in your vehicle service information.

Common causes

• Control circuit shorted to power
• Open connection in a monitored circuit
• Faulty regulator solenoid

Symptoms

• Hard starting or no start
• Reduced power or limp mode
• Check engine light

Diagnostic focus

Do not apply battery voltage directly to the regulator as a quick test. These electronically controlled valves can be damaged by an improvised power supply.

Can I keep driving with P0004?

Severity: High Avoid driving if the engine stalls, leaks fuel, or runs roughly. High-pressure fuel testing belongs with a qualified technician; never loosen a fuel rail or injector pipe to check pressure.

If the check engine light is flashing or the car runs badly, stop driving and have it checked.

Typical fixes

• Inspect the regulator harness and plug
• Check for short-to-power or open wiring according to the manufacturer circuit design and test the solenoid to specification.
• Replace only the valve or wiring proven faulty

Sources & review

• OBD-Codes.com: P0004
• TroubleCodes.net: generic code definitions

Definitions and diagnostic background checked 2026-11-06. Generic guidance, not a substitute for the service procedure for your exact year, engine, and transmission.