P2623 indicates the PCM has detected an open or excessively high-resistance condition in the electrical circuit for the injector control pressure regulator, often called the injection pressure regulator (IPR). This solenoid controls high-pressure oil used to actuate the fuel injectors, so an open circuit prevents the PCM from regulating injection control pressure. The result is typically poor running, hard starting, or a no-start condition.
The solenoid coil can break internally or its terminals can fail, producing an open circuit that the PCM detects when it commands the regulator. This is the most common component-level cause of P2623.
Heat, vibration, rubbing, or corrosion can break a wire, damage insulation, or push out a pin in the harness or connector, interrupting current flow to the solenoid.
Corroded, loose, oil-contaminated, or damaged terminals can raise circuit resistance enough that the PCM interprets the circuit as open.
A blown fuse, faulty relay, compromised ground path, or poor battery feed can prevent the solenoid from energizing and set the code.
Rarely, the transistor or driver inside the PCM that switches the regulator circuit fails; this should only be considered after the solenoid, wiring, connectors, and power/ground are proven good.
It is not advisable. An open regulator circuit can cause hard starting, stalling, or a no-start condition and may leave the vehicle stranded.
No. The solenoid is the most likely failed part, but damaged wiring, connector corrosion, or power and ground faults can set the same code and should be checked first.
Usually no. PCM driver failure is uncommon for this code; most cases are caused by a bad regulator solenoid or an open in the wiring/connector. Only suspect the PCM after the solenoid, harness, power, and grounds have been thoroughly tested.
Yes. If the regulator circuit is open, the PCM cannot command it, and the high-pressure oil system may fail to build the pressure needed to operate the injectors properly.