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P codepowertrainMedium severity

P0026Intake Valve Control Solenoid Circuit Range/Performance (Bank 1)

The Bank 1 intake valve control solenoid circuit is responding, but its behavior is outside the range the computer expects.

Definition

On engines with variable intake valve lift or timing (such as Subaru AVCS/i-AVLS systems), the PCM monitors the Bank 1 intake valve control solenoid circuit and the resulting valve response. P0026 sets when the circuit's electrical values or the system's mechanical response is out of the expected range even though the circuit is not fully open or shorted. Drivers may notice reduced power, rough idle, or poor fuel economy, and the MIL will be illuminated; some vehicles restrict performance until the fault is repaired.

Common causes

  • Low engine oil level or wrong viscosity restricting solenoid/actuator response
  • Sticking or contaminated intake valve control (oil control) solenoid on Bank 1
  • Clogged oil passages or screen at the solenoid from sludge
  • High resistance, chafed wiring, or a corroded connector in the solenoid circuit
  • Failing oil pressure switch/sensor used by the valve lift system
  • Internal solenoid winding drifting out of resistance specification

Common misdiagnoses

  • Replacing the solenoid when low or degraded oil is the root cause
  • Replacing camshaft position sensors that are unrelated to the fault
  • Replacing the PCM for what is a wiring or oil supply problem
  • Performing timing chain/belt work when the valve control hardware itself is at fault

Troubleshooting steps

  1. 1.Verify oil level and condition

    Confirm the correct level and factory-specified viscosity; change sludged oil and retest, since dirty oil is the most common trigger for valve control performance codes.

  2. 2.Measure solenoid resistance

    Disconnect the Bank 1 intake valve control solenoid and check winding resistance against spec (commonly around 6-12 ohms) plus no continuity to ground.

  3. 3.Inspect wiring and connector

    Check for chafed insulation, bent pins, and oil-contaminated terminals between the solenoid and PCM, and load-test the circuit rather than relying on a simple continuity check.

  4. 4.Command the solenoid

    Use a bidirectional scan tool to actuate the solenoid and verify an audible click and a corresponding change in cam/valve response data.

  5. 5.Remove and inspect the solenoid

    Pull the solenoid, check its filter screen for debris, and verify the plunger moves freely; clean or replace as needed.

  6. 6.Check oil pressure to the actuator

    Verify mechanical oil pressure meets spec at operating temperature, since a worn pump or clogged passage can mimic a solenoid fault.

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