Cause
Open circuit in regulator control wiring
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.
Typically a moderate job.
Some of these codes mean you should stop driving
3 of the 5 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (5)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0004 Fuel Volume Regulator A Control Circuit High Likely for this code Stop driving High
- P0090 Fuel Pressure Regulator A Control Circuit/Open Likely for this code Stop driving High
- P0092 Fuel Pressure Regulator A Control Circuit High Likely for this code Stop driving High
- P2294 Fuel Pressure Regulator B Control Circuit/Open Likely for this code High
- P2296 Fuel Pressure Regulator B Control Circuit High Likely for this code High
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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