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Cylinder 12 Exhaust Valve Control Circuit/Open

Jump to the fix

Severity

High

Can I keep driving?

Avoid extended driving; visit a service soon.

First step

Retrieve all stored codes; several open-circuit codes on the same bank usually point at a shared connector or feed

  • PPowertrain
  • 3Manufacturer-specific
  • 4Ignition / Misfire
  • 93Sequence number

What does it mean?

P3493 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 12 Exhaust Valve Control Circuit/Open . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.

Symptoms

  • Check engine light (MIL) on with a stored circuit fault
  • Cylinder 12 does not switch valve modes, giving uneven running and a noticeable vibration
  • Reduced engine power, especially in the RPM band where the exhaust valve strategy normally changes
  • Slightly raised fuel consumption and a duller throttle response
  • Some vehicles restrict RPM or enter limp mode to protect the valvetrain
  • Ticking or irregular valvetrain noise if the actuator is stuck in one position

Likely causes

  • Broken or cut control wire in the valvetrain harness, often at a flex point near the cam cover
  • Solenoid connector not fully latched, or a terminal pushed out of the back of the connector body
  • Open winding inside the exhaust valve control solenoid
  • Corrosion on the terminals after coolant, oil or wash water has entered the connector
  • Rodent damage or previous repair splices that have separated
  • Missing ground or power feed on the supply side of the actuator circuit
  • PCM driver output no longer capable of energising the circuit

How to fix it

  1. Retrieve all stored codes; several open-circuit codes on the same bank usually point at a shared connector or feed
  2. Wiggle test the valvetrain harness with the scan tool watching the circuit status to catch an intermittent open
  3. Disconnect the solenoid and check the connector body for pushed-out terminals and green corrosion
  4. Measure the solenoid resistance; an infinite reading confirms an open winding
  5. Check continuity of the control wire from the PCM pin to the solenoid pin, and check the supply side for voltage with the ignition on
  6. Repair or replace the damaged section of the wiring harness rather than splicing over corroded conductors
  7. Fit a new solenoid only when the circuit has been proven continuous, then verify actuator operation with a scan tool command
  8. If circuit and component are good, back-probe the PCM connector while commanding the output to confirm the driver switches

Codes From the Same System

All Fault Codes

Related Similar Codes

This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.