What it means
During cold start, fuel pressure regulator A cannot maintain commanded pressure - actual rail pressure drops below the calibrated lower limit.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Fuel pressure regulator A controls rail pressure during cold start, and the control module compares actual pressure with its commanded target. This code sets when pressure falls below the allowed lower limit, indicating the system cannot maintain enough pressure in that operating condition.
Common causes
Most likely first.
- Fuel pressure regulator stuck open or unable to control pressure
- Fuel leak or injector leakage
- Wiring or connector fault affecting regulator control
Symptoms
- Check engine light on
- Hard start, no start, or stalling under load
- Power loss especially at high load or rpm
- Possible long cranking time
How to diagnose it
- Save freeze-frame data and check commanded versus actual rail pressure during the cold-start event, including how long the engine cranked.
- On a cold engine, observe pressure during cranking and start-up with a scan tool, comparing the result with the manufacturer's specification.
- Inspect regulator A's wiring and connector for loose, corroded, or damaged connections that could prevent proper control.
- Check for external fuel leaks and use the manufacturer's procedure to assess possible injector leakage or pressure loss.
- If the pressure sensor and wiring test correctly, evaluate whether regulator A is stuck open or otherwise unable to maintain commanded pressure.
Common fixes
- Repair a damaged or poorly connected regulator A wire or connector.
- Repair any confirmed external fuel leak.
- Replace leaking injectors if testing confirms they are bleeding off pressure.
- Replace regulator A if it cannot control pressure and the circuit is sound.
- Replace the pressure sensor only if it fails the manufacturer's accuracy test.
Can I keep driving?
Avoid high loads and do not rely on the vehicle for trips where a stall would be hazardous; low fuel pressure can cause power loss, stalling, or a no-start. Stop driving if it stalls repeatedly or you detect a fuel leak.
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.