P0001 code meaning
Fuel Volume Regulator A Control Circuit/Open
Powertrain system Generic code P00xx codes Check engine light
What P0001 means
The fuel volume regulator (also called metering unit or suction control valve) is a solenoid valve on the inlet side of the high-pressure pump, used mainly on common-rail diesel engines. The engine control module pulses it to set how much fuel the pump draws in and delivers to the rail, and in this way controls rail pressure. P0001 is set when the control module detects that the control circuit of this valve is open, i.e. no plausible current flows when the valve is driven. Rail pressure can then no longer be controlled as intended. Whether the valve is open or closed without current depends on the design, so the same fault can cause excess pressure in one system and no pressure in another.
P0001 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P0001
- Check engine light on
- Engine cranks but does not start, or stalls (normally closed valve)
- Loss of power or limp mode (normally open valve)
- Additional rail pressure codes possible
Common causes of P0001
- Most likelyConnector at the regulator loose, corroded or unplugged
- PossibleSolenoid coil of the regulator open
- PossibleBroken wire in the harness, e.g. chafing or rodent damage
- Less likelyOutput driver in the engine control module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel volume regulatorHigh pressure fuel pumpFuel volume regulator wiring
What each part of P0001 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 01 | The exact fault in that area. |
What to do next
- Note P0001 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0001
What does P0001 mean?
P0001 means "Fuel Volume Regulator A Control Circuit/Open". The fuel volume regulator (also called metering unit or suction control valve) is a solenoid valve on the inlet side of the high-pressure pump, used mainly on common-rail diesel engines. It is a generic code, so it means the same on every make.
Is it safe to drive with P0001?
Drive gently and only to a workshop. With P0001 the car can go into limp mode (reduced power) to protect itself.
Will P0001 fail an emissions test?
Yes, it can. P0001 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0001 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0001 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.