P0004
Fuel Volume Regulator A Control Circuit High
The ECU sees the control voltage of fuel volume regulator A above the expected range, typically a short to power or open ground return.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Wiring shorted to battery voltageCommon
- Open ground return pathPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Fuel Volume Regulator
- FVR Wiring
P0004 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.