Drivers who encounter a sudden dip in acceleration, a hesitant start, or a rough‑idle condition will often see the Check‑Engine Light flash or stay illuminated. Those same symptoms appear when the powertrain control module (PCM) reports a Fuel Volume Regulator B Control Circuit High—the P2373 diagnostic trouble code. The PCM has detected a voltage level on the regulator’s control line that exceeds its designed range, indicating a fault that can limit fuel delivery to the second rail and reduce engine output. Because the regulator directly governs fuel pressure, even a brief over‑voltage condition can cause the engine to stumble under load. Early identification through a proper scan and circuit test prevents prolonged drivability loss and protects the fuel system from further stress.
These signs appear because the PCM limits fuel delivery when it believes the regulator is receiving an abnormal voltage signal.
The regulator contains a solenoid that modulates pressure on the second fuel rail. A shorted windings or a failed voltage‑sense circuit can drive the control line voltage above the PCM’s 5 V maximum, triggering P2373.
Corroded pins, damaged insulation, or a pinched harness can introduce excess voltage from the vehicle’s 12 V supply onto the regulator’s signal wire. A short to battery voltage instantly raises the signal level, while high resistance can cause voltage spikes during transient loads.
The PCM’s analog input stage that reads the regulator’s voltage may develop a leaky transistor or damaged ADC, causing it to register a high voltage even when the regulator is normal.
The driver that powers the high‑pressure pump can produce transient voltage spikes that couple into the regulator’s control line, especially if the driver’s suppression components are degraded.
A missing or weak ground at the regulator or PCM connector can shift the reference point for voltage measurement, making a normal signal appear high.
– Connect a compatible scan tool, confirm P2373, and note any additional fuel‑system codes (e.g., P0230, P0231) that may indicate broader issues.
– Examine the regulator’s wiring harness for frayed conductors, corrosion, or pinched sections.
– Check connector pins for bent terminals, oxidation, or missing pins.
– With the ignition ON and engine OFF, measure the regulator control line voltage relative to chassis ground. It should read between 0 V and ~5 V.
– Crank the engine; the voltage should remain within the same range. Any reading above 5.5 V indicates a high‑circuit condition.
– Perform a continuity test from the regulator signal wire to battery positive. A low resistance (< 10 Ω) suggests a short.
– Measure resistance to ground; high resistance (> 10 kΩ) may indicate an open circuit or poor grounding.
– If the wiring checks out, bench‑test the regulator (or use a live‑data stream) to verify that it can command fuel pressure changes without exceeding voltage limits.
– Substitute a known‑good PCM (if available) or use a PCM test harness to see if the voltage reading normalizes.
– If the fault follows the PCM, the internal input stage is likely defective.
– Wiring repair: Replace damaged harness sections, clean corroded connectors, and ensure solid grounds. Typical labor: 1–2 hours, parts $20–$80.
– Regulator replacement: Install a new Fuel Volume Regulator B; labor 1 hour, part cost $150–$300.
– PCM repair or replacement: If the PCM’s input circuit is at fault, consider a professional PCM repair (often $200–$400) or a full replacement.
– After any module replacement, the PCM must be programmed with the vehicle‑specific calibration. Flagship One provides VIN‑matched units pre‑programmed to factory specifications, eliminating dealer‑only reflash steps.
– Clear the P2373 and related codes, then perform a road test under varied loads. Verify that the Check‑Engine Light remains off and that power delivery is smooth.
If voltage testing repeatedly shows a high‑circuit condition despite clean wiring, the fault most often resides inside the regulator or PCM. While a repair may temporarily restore function, internal component degradation—such as burned solenoid windings or leaky analog inputs—tends to recur, leading to repeated diagnostics and reduced reliability.
Modern control modules are complex and integrated with security and immobilizer systems. Choosing a replacement isn’t only about the hardware; it’s about correct programming and compatibility. Flagship One specializes in VIN‑matched control modules, providing a plug‑and‑drive solution backed by warranty. Their units are pre‑programmed to the exact software version required for your vehicle, ensuring seamless integration and eliminating dealer‑only reflash delays.
Service Recommendation: Most issues related to this fault are diagnosed and corrected through inspection, wiring repair, and calibration rather than module replacement. For modules not typically replaced through aftermarket suppliers, diagnosis and repair should be performed by a certified automotive technician with access to factory service information and tooling.