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P3423 — Cylinder 3 Exhaust Valve Control Circuit Low

Manufacturer-specificPowertrain (engine & transmission)

OBD-II code P3423 indicates that the engine control module (PCM) has detected a low voltage condition in the control circuit for the exhaust valve actuator on cylinder 3. This typically involves variable valve timing or cylinder deactivation systems where exhaust valve operation is electronically controlled.

Symptoms

What causes it — most likely first

1. Faulty exhaust valve control solenoid (actuator)

The solenoid responsible for controlling the exhaust valve on cylinder 3 may be internally shorted, stuck, or mechanically failed, causing a low voltage signal.

2. Wiring or connector issues in the control circuit

Damaged, corroded, or shorted wiring, or a poor electrical connection at the solenoid or PCM connector, can cause a low voltage reading.

3. Exhaust valve actuator mechanical failure

The actuator mechanism (e.g., cam phaser, lifter, or rocker arm) may be seized, worn, or obstructed, preventing proper operation and affecting the circuit.

4. Low engine oil level or degraded oil

Insufficient or degraded engine oil can impair hydraulic operation of the exhaust valve control system, leading to circuit faults.

5. Faulty oil control valve or passages

Clogged or malfunctioning oil control valves or passages can restrict oil flow to the exhaust valve actuator, causing operational issues.

6. PCM (engine computer) failure (rare)

While uncommon, a fault in the PCM’s output driver circuit for the exhaust valve control could cause this code. This is typically a last-resort diagnosis after all other causes are ruled out.

How it's diagnosed

  1. Verify the code with an OBD-II scanner and check for related codes (e.g., misfire, oil pressure, or VVT codes).
  2. Inspect the engine oil level and condition; top up or replace oil if necessary, ensuring the correct viscosity is used.
  3. Visually inspect the wiring harness and connectors for the cylinder 3 exhaust valve control solenoid for damage, corrosion, or loose connections.
  4. Test the exhaust valve control solenoid for proper resistance and operation using a multimeter and manufacturer specifications.
  5. Check the mechanical operation of the exhaust valve actuator (e.g., cam phaser, lifter, or rocker arm) for wear, seizure, or obstruction.
  6. If all other causes are ruled out, perform a PCM output test or use a scope to verify the PCM is sending the correct control signal.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP3420 — Cylinder 3 Deactivationintake Valve CoP3421 — Cylinder 3 Exhaust Valve Control CircuP3422 — Cylinder 3 Exhaust Valve Control CircuP3424 — Cylinder 3 Exhaust Valve Control CircuP3425 — Cylinder 4 Deactivationintake Valve CoP3426 — Cylinder 4 Deactivationintake Valve Co

Frequently asked

Is the PCM usually the cause of P3423?

No, the PCM is rarely the cause of P3423. This code is almost always triggered by a faulty solenoid, wiring issue, or mechanical failure in the exhaust valve control system. PCM replacement should only be considered after all other potential causes have been thoroughly ruled out.

Can I drive with P3423?

Driving with P3423 may cause further damage to the exhaust valve control system or related components, especially if the engine is misfiring or running poorly. It is recommended to diagnose and repair the issue as soon as possible.

Will changing the oil fix P3423?

If the code is caused by low or degraded engine oil, an oil change may resolve the issue. However, if the problem is due to a faulty solenoid, wiring, or mechanical failure, an oil change alone will not fix it.

How do I test the exhaust valve control solenoid?

To test the solenoid, disconnect its electrical connector and measure the resistance across its terminals using a multimeter. Compare the reading to the manufacturer’s specifications. Additionally, check for proper voltage at the connector when the engine is running.