P0003 moderate

Fuel Volume Regulator Control Circuit Low

The P0003 code means the vehicle's onboard diagnostic system has detected: Fuel Volume Regulator Control Circuit Low. This is a moderate severity code.

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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
Low fuel rail pressure
Engine misfires under load
Difficulty starting

Probable Causes (Ranked by Likelihood)

Short to ground in fuel volume regulator wiring Very High
Failed fuel volume regulator solenoid (shorted internally) High
Damaged wiring harness near exhaust or moving parts Moderate
ECM driver circuit failure Low

Step-by-Step Diagnostic Procedure

Disconnect the fuel volume regulator connector and measure circuit voltage from ECM side with key on
Check wiring from ECM to regulator for shorts to ground using an ohmmeter
Measure regulator solenoid resistance; a reading significantly below spec indicates an internal short
Inspect wiring harness routing for contact with hot exhaust components or moving parts

Frequently Asked Questions

What does circuit low mean for P0003?

Circuit low means the ECM is detecting a voltage in the fuel volume regulator control circuit that is below the minimum expected threshold. This usually indicates a short to ground in the wiring or a failed solenoid with reduced internal resistance.

Can I repair the wiring myself?

If you can locate the short to ground in the wiring harness, the repair itself is straightforward using solder and heat shrink. However, diagnosing the exact location of the short requires electrical testing skills and access to wiring diagrams.

Is this code related to low fuel pressure codes?

Yes. P0003 affects the fuel volume regulator which directly controls rail pressure. If this code is present alongside P0087 (fuel rail pressure too low), the regulator circuit fault is likely the root cause of both.