Fuel Volume Regulator Control Circuit High
The P0004 code means the vehicle's onboard diagnostic system has detected: Fuel Volume Regulator Control Circuit High. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $150 - $600 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Excessive fuel rail pressure
- Engine runs rough
- Black smoke from exhaust
Probable Causes (Ranked by Likelihood)
- Short to power in fuel volume regulator wiring Very High
- Failed fuel volume regulator stuck in high flow position High
- Corroded ground connection for regulator circuit Moderate
- ECM internal fault on regulator driver Low
Frequently Asked Questions
What does circuit high mean for P0004?
Circuit high means the ECM is detecting higher voltage than expected in the fuel volume regulator circuit. This typically indicates a short to battery voltage in the wiring or a faulty regulator solenoid with excessive resistance.
Can excessive fuel rail pressure damage my engine?
Yes. Excessively high fuel rail pressure can cause injectors to deliver too much fuel, leading to engine damage over time. It can also stress fuel system seals and gaskets, potentially causing leaks.
Is P0004 common after fuel system service?
It can occur if a connector was not properly reconnected or if wiring was pinched during reassembly. Always double-check all electrical connections after any fuel system service near the high-pressure pump.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Disconnect the fuel volume regulator and check if the code clears; if it does, the regulator is likely shorted internally
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Measure voltage at the regulator connector with it unplugged; voltage above spec indicates a short to power in the harness
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Verify the regulator ground path with an ohmmeter; resistance should be near zero
-
Monitor fuel rail pressure with regulator disconnected vs connected to determine if regulator is stuck open
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- 2010-2020 Volkswagen Passat TDI
- 2012-2019 Audi A3 TDI
- 2013-2020 Chevrolet Equinox Diesel
- 2014-2020 Jeep Grand Cherokee EcoDiesel
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