P0001
Fuel Volume Regulator A Control Circuit/Open
Fuel delivery
Generic OBD-II
High
What it means
P0001 means the ECM has detected an open in the control circuit for fuel volume regulator A — the valve that meters how much fuel the high-pressure pump delivers, common on diesel and direct-injection engines. With the circuit open, the ECM can't regulate fuel pressure, which can cause hard starting, low power, or even a no-start on affected systems.
High
Can I keep driving? Possibly not reliably — an open fuel-volume-regulator circuit can leave the ECM unable to control fuel pressure, causing hard starting or a limp-mode power loss, so get it diagnosed before it strands you.
Common symptoms
What you'll notice
- Check-engine light on
- Hard starting or extended cranking
- Reduced power or limp mode
- Rough idle or hesitation
- Decreased fuel economy
Common causes
Most likely first
- Open or shorted wiring/connector in the fuel volume regulator control circuitLikely
- Failed fuel volume regulator (solenoid)Common
- Corroded or loose connector at the regulatorCommon
- Failed ECM or regulator driver (rare)Less often
How to diagnose & fix
Work through it in order
- Scan for freeze-frame data and confirm the code.
- Inspect the regulator connector and wiring for opens, chafing, or corrosion.
- Measure the regulator solenoid resistance and check for power and ground.
- Repair wiring or replace the regulator as indicated.
- Clear and retest; only consider the ECM if the circuit checks good.
FAQ
Quick answers
Is it safe to drive with P0001?+
Risky — the engine may start and run, but an uncontrolled fuel-pressure circuit can drop you into limp mode or a no-start without warning. Diagnose it promptly.
Can I just clear P0001?+
It comes back as soon as the ECM re-tests the circuit, since clearing doesn't repair the open. Fix the wiring or regulator first.
Related codes
Often seen with P0001
Read & clear P0001 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX