Some steps might change based on particular vehicles that require further equipment in order to be precisely carried out. These procedures require a digital multimeter and vehicle-specific technical reference documents. For most the cases, you must follow some of these steps to troubleshoot the P3401 OBDII diagnostic code:
- Consult the TSB (Technical Service Bulletins).
- Verify that the engine oil has the proper level, as well as that it does not present contamination. In any of these cases, make the necessary corrections.
- Check that the engine oil passages are free of obstructions. If you detect elements that impede the oil flow, make the necessary adjustments.
- Check the cables, connectors, and other components of the electrical circuit. If these present inconsistencies, repair them or replace them if necessary.
- Using a multimeter perform voltage checks on the intake valve circuit. Verify that the supply signal, ground, and reference voltage are as indicated in the service manual. Repair if inconsistencies are found.
- Verify that the resistance of the intake valve deactivation solenoid is adequate for proper system performance. If this level is not within the expected range, replace the solenoid.
Also, it is important to keep in mind that the reference voltage and permissible ranges could differ based on the particular circuit and vehicle configuration. Detailed technical data will include troubleshooting charts and the proper sequence of steps to assist you in performing an effective diagnosis.
If this procedure senses that a power supply or ground is missing, a continuity test might be needed to confirm the integrity of the wiring, connectors, and other components. Continuity tests should always be conducted with power disconnected from the circuit, and normal readings for wiring and connections should be 0 ohms resistance. Resistance or lack of continuity indicates a fault in the wiring that is open, shorted, or corroded and needs to be repaired or replaced.