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P0449 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


An evaporative emission control system vent valve/solenoid circuit is put in place to prevent fuel vapors from escaping from the tank and fuel system into the surrounding atmosphere. The system is found on any vehicle dating back to 1996. This is a vital system because fuel vapors are dense in hydrocarbons that increase pollution into the air. When operating efficiently, the EVAP system captures the emissions and fumes produced while the fuel is processed.

The design of this system varies according to the makeup of the engine. A malfunction within the system must be analyzed in order to be detected and addressed.


The OBD2 code, P0449, indicates that the evaporative emission control system vent valve or solenoid has malfunctioned. The ECU senses this fault and sends a signal for the “Check Engine Light” to light up on the dashboard. This is a generic signal that serves as a first step in determining a problem within the emissions system. The main causes for this malfunction are listed below.


There are a few common reasons that would trigger a P0449 DTC code. There may be a short or opening in the wiring harness. There may be an intermittent electrical connection or one that is of poor quality. This could be because of a weak design or because of wear and tear over time.

Another cause may be a failed charcoal canister vent valve. There may be a crack or hole that has developed within the piece.

Finally, the signaling system itself may have a short or may have gone bad for some reason. This would give a false signal and would need to be replaced.


Commonly, there are few apparent symptoms of an EVAP system failure. The driver may detect a fuel smell coming from the vehicle while driving. Fuel efficiency may also drop over time.

The main indicator of an issue is an illuminated “Check Engine LIght.” Once a problem has been detected, the vehicle should be put through a diagnostic process in order to determine the source of the failure.


Follow the steps below to diagnose the EVAP issue:

  1. Use a professional scan tool to determine codes stored in the ECU, including the history or other pending codes.
  2. Analyze the freeze frame data associated with the codes. This will give information about all aspects of the vehicle’s performance when the malfunction caused the “Check Engine Light” to illuminate.
  3. Clear all of the codes.
  4. Test run the vehicle to observe any symptoms that are present.
  5. Visually inspect the vent valve and wiring harness to look for any damage. The majority of the problems will be found in one of these areas.
  6. If nothing is found during the visual inspection, use an advanced scan tool to test the EVAP functions. Enable the vent valve to function, checking for proper execution. Check for continuity between the ECU and vent wiring in case the problem is within the indicator itself. Conduct a test on the ECU to note any malfunctions.

Common mistakes

Errors can occur when diagnosing any code if procedures are not followed in order or are omitted. All components must be tested thoroughly for proper operation before they are replaced. Otherwise, working parts may be replaced unnecessarily.

How serious is this?

The P0449 code is an emissions control indicator and will cause the vehicle to fail OBD2 based emissions testing. In addition to failing the emissions requirements, the fuel odor may irritate some drivers. Fuel and overall efficiency will be negatively affected over time.

While this warning code should not prevent standard vehicle operation, it should still be addressed and repaired as quickly as possible.

What repairs can fix the code?

Here is a helpful checklist of repairs that can address and rectify the malfunction once identified. (This list coordinates with the diagnostic steps listed above, and should be done as needed, in order.)

  1. Replacing or repairing the wiring harness. Look for burnt or worn wiring before taking this step.
  2. Changing the charcoal canister vent valve. This step will be needed if cracks or worn places are located on the valve.
  3. Repairing or replacing faulty electrical connections. Each component should be tested for connectivity.
  4. Changing out a faulty ECU. If no problems from the previous steps are found, the ECU is most likely faulty and can be replaced.

Related codes

Some related codes are P0420, P0446, and very often P0440.


The OBD2 code, P0449, is a generic code that signals a problem with the emission control system. Though not an immediate threat to the vehicle’s driving ability or safety, it does indicate there is a malfunction that needs to be diagnosed and corrected. By using the right scan tool and following a step-by-step diagnostic procedure, you will return to maximum efficiency without unnecessary repairs and cost.

P0449 Code – What Does It Mean & How To Fix It