Powertrain, generic (extended)

P2371 Fuel Volume Regulator B Control Circuit Performance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modePossible

P2371 is a functional fault of the second fuel volume regulator: the control circuit works electrically, but the valve does not achieve what the ECM asks of it. No manufacturer publishes a definition for regulator B, so the A side helps. Deutz's EMR controller, for example, compares the regulator current with its set point and records separate faults when it stays above or below it, plus a plausibility check of the current. Ford's 2023 diesel uses its P0002 for a different case – the driver stage in the ECM getting hotter than 170 °C. CARB also requires a fault when fuel pressure control reaches its limits and the commanded pressure can no longer be delivered. A sticking valve, dirt in the fuel or a worn pump are the usual causes.

Likely causes

Regulator B valve sticking from dirt or wear

High-pressure pump B worn

ECM driver stage overheating

Symptoms

Check engine light on
Rail pressure fluctuates or misses its target
Reduced power under load

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–3,000

Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel volume regulator bhigh pressure fuel pumpfuel volume regulator wiring

References: law.cornell.edu, fordservicecontent.com, serdia.deutz.com.