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P3493 OBD-II Trouble Code: Cylinder 12 Exhaust Valve Control Malfunction

check engine light

P3493 code definition

P3493 is the OBD-II code for Cylinder 12 Exhaust Valve Ctrl Circuit/Open. Cylinder 12 tells you that the issue is occurring at cylinder 12.

What the P3493 code means

A cylinder exhaust valve vents fuel vapors produced by the engine. The vehicle’s computer controls when the valves open and close, as well as monitors whether the timing meets the expected specifications. When the computer receives a signal from the cylinder 12 exhaust valve which is outside of the normal range, a fault in the circuit is detected and the vehicle will set the P3493 code.

What causes the P3493 code?

This code may set due to:

  • Low oil pressure resulting from insufficient oil level
  • A faulty exhaust valve control solenoid
  • A short or open in the valve control solenoid wiring
  • A loose connection from the exhaust valve to the solenoid
  • Clogged oil passageways
  • A timing belt or chain that needs adjusting
  • A camshaft actuator malfunction

Very rarely, the root of the problem could be a bad PCM (powertrain control module) or ECM (engine control module). This code is typically due to other faults like bad wiring, so all other diagnostic avenues should be exhausted before turning to computer failure.

What are the symptoms of the P3493 code?

The Check Engine Light will likely come on, you may experience poor acceleration, and fuel efficiency may suffer. When a cylinder exhaust valve code sets, the variable valve timing system in the vehicle typically disables.

How does a mechanic diagnose the P3493 code?

Your technician may perform the following steps in order to find the problem:

  • Verify the code using an advanced scan tool, noting any concurrent codes and recording the freeze frame data
  • Diagnose and repair any codes which occurred before P3493
  • Clear all trouble codes and road test the vehicle to see if they return
  • Visually inspect all wiring, connectors, and harnesses to check for compromised circuitry or loose connections
  • Test the exhaust valve control solenoid and sensor

How serious is the P3493 code?

The vehicle will still operate, however an exhaust valve circuit malfunction can impair the power needed to drive safely. It’s wise to have this code diagnosed and addressed by a qualified technician as soon as possible in order to prevent dangerous driving conditions as well as a chain reaction of potential future damage to other components.

What repairs can fix the P3493 code?

Steps your technician may perform to resolve this DTC may include:

Additional comments for consideration regarding the P3493 code

Whenever a DTC is set involving the complex parts of the engine, cylinders, and valves, the diagnostic process can become complicated. A qualified mechanic has the necessary specialized tools to find the problem quickly and efficiently, and get you back on the road.

In addition, technicians keep up to date on current service bulletins which may offer guidance on common problems which occur in particular vehicle makes and models. This knowledge allows your mechanic to start by identifying potential common problems which may be affecting your vehicle.

Need help with a P3493 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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