P0449 OBD-II Trouble Code: Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction

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P0449 code definition

P0449 is a general OBD2 diagnostic trouble code indicating an issue with the EVAP vent control circuit. This code may be seen with other EVAP system codes

What the P0449 code means

The P0449 DTC means that the evaporative emission control system vent valve or solenoid has a malfunction. The ECU detects this fault and causes the Check Engine Light to be illuminated on the dashboard.

What causes the P0449 code?

  • Short or open in the wiring harness
  • Electrical connection that is intermittent or of poor quality
  • Failed charcoal canister vent valve
  • Faulty ECU

What are the symptoms of the P0449 code?

  • Commonly there will be no felt symptoms while driving.
  • The Check Engine Light will be illuminated on the dash board.
  • The driver may notice a slight fuel odor coming from the vehicle.

How does a mechanic diagnose the P0449 code?

  • Uses a scan tool to check for any codes stored in the ECU including history or pending codes

  • Take note of the freeze frame data associated with the codes this is the conditions the vehicle was under when the malfunction set the Check Engine Light

  • Clears all of the codes

  • Takes the vehicle on a road test to confirm any symptoms that are present

  • Performs a visual inspection of the wiring harness and the vent valve looking for any damage

  • Uses an advanced scan tool to operate the EVAP functions and enables the vent valve to function, checking for proper operation

  • Checks for continuity between the vent wiring and ECU

  • Perform a test on the ECU

Common mistakes when diagnosing the P0449 code

Mistakes can be made with any code when steps are not followed or aren’t completed at all. All components must be tested for proper operation thoroughly before they are replaced otherwise perfectly working parts may be replaced unnecessarily.

How serious is the P0449 code?

P0449 is an emissions control code and will cause the vehicle to fail OBD2 based emissions. Other than failing the emissions the fuel odor may bother some drivers. This code should not prevent normal vehicle operation but should still be repaired ASAP.

What repairs can fix the P0449 code?

  • Repairing or replacing the wiring harness
  • Replacing the charcoal canister vent valve
  • Repairing faulty electrical connections
  • Replacing faulty ECU

Additional comments for consideration regarding the P0449 code

Advanced level scans are extremely helpful when diagnosing EVAP system codes. These scan tools allow technicians to use the vehicle's EVAP self test procedures and let the user command on and off EVAP valves and solenoids. WIthout an advanced level scan tool these procedures can not be performed and diagnosis becomes much more difficult.

Need help with a P0449 code?

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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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