What it means
The ECU sees implausible feedback on the control loop for fuel volume regulator B - duty cycle does not match measured rail pressure response. The regulator either reacts too slowly, sticks, or has shifted from its calibration.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Fuel volume regulator B meters fuel through the high-pressure pump or fuel system under ECU control. The ECU compares its command to regulator B with the resulting fuel-rail pressure response; P2371 sets when that response is too slow or otherwise does not match the expected behavior.
Common causes
Most likely first.
- Regulator stem sticking due to debris or wear
- High-pressure pump wear changes regulator response
Symptoms
- Check-engine light
- Hard starting
- Loss of power
- Hesitation or poor acceleration
How to diagnose it
- Read freeze-frame data and live rail-pressure and regulator-command data to see when regulator B's response diverges from the ECU command.
- Check for related fuel-pressure or regulator codes that could point to a broader pump or supply problem.
- Inspect regulator B and its connector for contamination, damage, loose terminals, or signs of fuel leakage.
- Check the fuel supply and rail-pressure behavior under the conditions recorded in the freeze frame, following the manufacturer's procedure.
- If wiring and supply checks pass, test regulator B for sticking or delayed response and assess high-pressure pump condition to the manufacturer's specification.
Common fixes
- Clean or repair a contaminated or loose regulator B connector.
- Repair damaged wiring or terminals in regulator B's control circuit.
- Replace regulator B if it sticks or responds outside the manufacturer's specification.
- Repair or replace a worn high-pressure pump if testing confirms it is causing the delayed pressure response.
Can I keep driving?
Avoid hard acceleration and long trips because poor fuel-pressure control can cause hesitation, stalling, or loss of power. If it is difficult to start or power drops sharply, stop driving and arrange repair.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.