P2623: Injector Control Pressure Regulator Circuit Open
What to do
The likely picture is an engine that cranks strongly and will not start, or one that starts and runs badly.
The critical thing to say is that on this engine the injectors are driven by high-pressure engine oil, not by fuel pressure, and this code is about the valve that controls that oil. A no-start here looks exactly like fuel starvation and is not one. Fuel pumps, filters and injectors fitted on the strength of it are money wasted — the fuel system is doing its job.
Ask for the regulator's wiring and connector to be checked, and be ready to discuss when the oil was last changed and what grade went in. On this type of engine the oil is part of the injection system, so its condition is a diagnostic question rather than a service one, and a valve stuck in varnish behaves exactly like a failed valve.
What this code means
An open circuit in the control of the injector control pressure regulator.
This belongs to the hydraulically actuated injection system introduced at P2283, where engine oil rather than fuel provides the force that injects. A high-pressure oil pump raises engine oil to well over a thousand bar and delivers it to a piston above each injector; the fuel system supplies fuel at modest pressure and does none of the injecting. Fuel is the payload; oil is the force.
The P228x codes describe the sensor that measures that oil pressure. This one describes the valve that controls it — the regulator that decides how much of the pump's output reaches the injectors, and therefore how hard they fire. It is the actuator to their measurement.
With an open control circuit the module cannot regulate at all, and the valve goes to whatever position it adopts unpowered. That is normally minimum pressure, and minimum pressure on this kind of engine means the injectors cannot reach their firing threshold. The result is the situation P2291 describes in detail and is worth repeating because of how convincingly it misleads: the engine cranks strongly, has fuel, has compression, and does not start. Everything a fuel-starvation diagnosis looks for is present and correct, so fuel pumps, filters and injectors get changed while the actual problem is oil.
The circuit is the thing to test first — the connector, the wiring, the regulator's winding — but oil condition belongs in the conversation immediately afterwards, for the reason set out at P2283: on this system oil is a working fluid rather than a maintenance item, and a regulator sticking in varnish behaves like a failed one.
Likely causes
Start here
- Open circuit in control wiring · moderate
- Corroded or loose connector · easy
- Faulty injection pressure regulator · moderate
Less common
- Damaged wiring harness · moderate
- Low or dirty engine oil · easy
Rare
- Faulty engine control module · specialist
Symptoms
Components involved
Information, not instruction
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