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DTC codes / P26xx · Computer and output circuits / P2623

P2623Injector Control Pressure Regulator Circuit/Open

P2623 indicates that the engine control module (ECM) has detected an open circuit or excessive resistance in the electrical path for the injector control pressure regulator, which is the solenoid valve that adjusts oil pressure feeding the fuel injectors on many diesel engines. The ECM monitors the regulator circuit and sets this code when the expected voltage or current is outside the normal range, meaning the regulator is not being commanded or is not responding electrically.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • Illuminated check engine light, often with no other noticeable symptoms
  • Rough idle or misfire, especially when the engine is cold
  • Reduced engine power or limp mode
  • Hard starting or extended cranking before the engine fires
  • Poor fuel economy or increased exhaust smoke
  • Stalling or hesitation during acceleration

Common causes, most likely first

  1. Damaged or disconnected electrical connector at the injector control pressure regulator
  2. Open or shorted wire in the regulator circuit (power, ground, or signal)
  3. Failed injector control pressure regulator solenoid
  4. Corroded or loose pins in the regulator harness connector
  5. Blown fuse or faulty relay supplying power to the regulator circuit
  6. Faulty engine control module (ECM) driver circuit (less common)

How to diagnose and fix it

  1. Inspect the regulator connector and harness for obvious damage, corrosion, or loose pins; clean and reseat as needed
  2. Check the fuse and relay that supply power to the injector control pressure regulator circuit
  3. Measure resistance across the regulator solenoid terminals and compare to the manufacturer's specification
  4. Backprobe the regulator connector and check for battery voltage on the power side with the key on
  5. Perform a voltage drop test on the ground circuit to rule out excessive resistance
  6. Check continuity and resistance of the signal wire between the regulator and the ECM, looking for opens or shorts
  7. If all electrical checks pass, suspect the ECM; test with a known-good unit or consult a specialist before replacement

What the code does not always mean

  • A P2623 can be set by a simple loose connector that only loses contact under vibration, so always wiggle-test the harness while watching live data.
  • On many diesel engines, the injector control pressure regulator is part of the high-pressure oil pump and a mechanical failure inside the pump can mimic an electrical open circuit.
  • The ECM may set this code intermittently if the regulator coil resistance drifts with temperature, so a cold resistance check alone can miss the fault.
  • A weak battery or poor ground can cause the ECM to misreport a regulator circuit fault, so always verify battery and ground integrity first.
  • Replacing the regulator without checking the harness is a common misdiagnosis; the wiring and connectors fail more often than the solenoid itself.

Can I keep driving with P2623?

You can usually drive the vehicle with this code, but expect reduced power and possible stalling; avoid heavy loads and long trips until the fault is repaired, and do not ignore it because continued driving with a failed regulator can damage the high-pressure oil pump or injectors.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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