Circuito abierto en el mando del regulador

A break in the control wiring to a fuel volume or pressure regulator, so the module's command never arrives. It is distinct from a general control-wiring fault by which circuit it names — this one carries a pulse-width signal to a regulator that meters fuel, so an open circuit means no fuel control at all rather than a degraded function.

The engine's response is protective and abrupt. With no regulator control the module cannot govern rail pressure, so it will refuse to run or drop to a strategy that limits it severely. A no-start with a regulator circuit code is this, and the pump and the regulator itself are usually fine.

Test at the regulator's connector, which splits the circuit in one measurement. A command signal present at the plug puts the fault in the winding; absent puts it upstream in the harness or the driver. These regulators sit on or beside the high pressure pump, so the harness runs through a hot, vibrating area — inspect where it passes a bracket or crosses the engine, since the break is usually mechanical and visible once the loom is opened.