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P3412 — Cylinder 2 Deactivationintake Valve Control Circuit High

Manufacturer-specificPowertrain (engine & transmission)

P3412 indicates that the engine control module has detected an abnormal high voltage condition on the cylinder‑2 deactivation (intake‑valve) control circuit. In engines that use cylinder‑deactivation (such as active‑fuel‑management), a solenoid or oil‑control valve that turns the intake valve on/off for cylinder 2 is not responding as expected, causing the circuit to read higher than the commanded level.

Symptoms

What causes it — most likely first

1. Faulty cylinder‑2 valve‑lift oil‑control solenoid

The solenoid that routes oil pressure to the cylinder‑2 lifters can seize, short internally, or have an open winding, causing a high‑voltage reading on its control circuit.

2. Wiring or connector problem

A short to battery voltage, open ground, broken wire, or corroded connector in the harness feeding the solenoid can pull the circuit high.

3. Low oil pressure or contaminated oil

If the engine’s oil pressure is insufficient or the oil is thick/sludged, the hydraulic solenoid may not actuate correctly, resulting in an abnormal circuit voltage.

4. Faulty oil‑pressure sensor or signal

An inaccurate oil‑pressure reading can cause the PCM to command an improper voltage to the solenoid, though this is a less common root cause.

5. Mechanical valve‑train issue

Severe carbon buildup or a stuck valve can prevent proper valve operation, which may indirectly affect the solenoid circuit.

6. PCM/ECM internal fault

Rarely, the engine computer itself may mis‑interpret the circuit voltage or fail to provide the correct control signal; this should be ruled out only after all other components are verified.

How it's diagnosed

  1. Connect an OBD‑II scanner, record P3412 and freeze‑frame data, then clear the code and see if it returns after a test drive.
  2. Visually inspect the cylinder‑2 valve‑lift solenoid wiring and connector for damage, corrosion, or looseness.
  3. With the key on, measure the voltage on the solenoid’s control circuit; compare to the expected reference voltage (typically 5 V or 12 V depending on vehicle).
  4. Check the solenoid’s resistance with a multimeter and compare to the manufacturer’s specification; also test for shorts to ground or battery.
  5. Verify engine oil pressure, level, and condition; ensure the oil system can supply the required pressure to the solenoid.
  6. If wiring and solenoid check out, use an oscilloscope or advanced scan tool to monitor the PCM’s command signal; absence of the signal may point to a PCM issue.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP3410 — Cylinder 2 Deactivationintake Valve CoP3411 — Cylinder 2 Deactivationintake Valve CoP3413 — Cylinder 2 Exhaust Valve Control CircuP3414 — Cylinder 2 Exhaust Valve Control CircuP3415 — Cylinder 2 Exhaust Valve Control CircuP3416 — Cylinder 2 Exhaust Valve Control Circu

Frequently asked

Is the PCM (engine computer) usually at fault for P3412?

No. The PCM rarely fails for this code. Most of the time the problem is the solenoid, its wiring, or insufficient oil pressure. Replacing the PCM should only be considered after those components have been ruled out.

Can I continue driving with P3412 set?

The vehicle will still run, but you may notice poorer fuel economy, rough idle, or extra vibration. It is advisable to diagnose and repair the issue promptly to restore normal cylinder‑deactivation operation.

Will clearing the code fix the problem?

Clearing the code resets the indicator light, but if the underlying fault (e.g., a bad solenoid) is still present, the code will return after a few driving cycles.

Could low oil level cause P3412?

Yes. The cylinder‑deactivation system relies on hydraulic oil pressure; if the oil level is low or the oil is degraded, the solenoid may not function correctly, leading to a high‑voltage reading on the circuit.