P0001: the fuel volume regulator circuit isn't reading right
Many diesel and some direct-injection engines meter fuel into the high-pressure pump using a fuel volume regulator, a valve the engine control unit operates electrically to set exactly how much fuel the pump sends onward. This code means the control unit isn't seeing the electrical signal it expects from that valve's circuit, consistent with an open circuit — a break somewhere in that circuit, so nothing gets through. It doesn't say whether the valve, its wiring or its plug is behind the fault, only that the circuit isn't behaving as it should.
You might notice
- The engine warning light comes on
- The engine may not start, run roughly, or lose power
- fuel volume regulator
- — a valve that sets exactly how much fuel the high-pressure pump sends onward
- open circuit
- — a break somewhere in a circuit, so nothing gets through it
What this code means for driving
Stop driving
The high-pressure fuel system has logged a pressure fault or a leak.
Stop driving now — leave it where it is until a garage has checked it. If you smell fuel or you see fuel under the car, that's an emergency: pull over immediately.
On a car with a combustion engine: A leak on a high-pressure fuel system is a fire risk. Do not investigate it yourself.
This is what P0001 means taken alone, and that part won't change no matter what else your scan turns up. What's actually causing it can still depend on the rest of your codes. Read it with your other codes.
What the code itself says
P0001 is a powertrain (engine, gearbox and drive system) code, and the 0 after the letter means it is a generic code with a standard meaning.
Grouped here as: Engine running, fuelling and misfires — Air metering, fuelling, ignition, misfire, idle, boost, knock, oxygen sensors and the catalyst, all working together in the running engine. That grouping is ours, to help explain the code. The code's official family is the letter at the start.
This page is generic. Your car isn't.
A code on its own only tells you what the sensor saw, not what's actually wrong — and that changes next to your other codes. Read this one together with the rest of your scan and we'll work out what's really going on.
Stop reading. Start diagnosing.
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