How to Fix Code P0449: Causes, Symptoms & Fixes

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If you are driving and suddenly see the check engine light turn on, it can cause concern. One of the most common codes you can get is code P0449. So what does this trouble code mean?

This guide will walk you through the steps you need to take to diagnose and fix the trouble code P0449. Read on!

What is Code P0449?

The P0499 is a generic code indicating a problem with the Evaporative Emission System (EVAP) vent control. The EVAP system is responsible for preventing fuel vapors from the tank from escaping into the atmosphere. When this system malfunctions, this triggers the code P0449.

Symptoms of Code P0449

Usually, the code P0449 has no symptoms. However, the code may cause the check engine light to illuminate in some cases. Aside from the check engine light turning on, you will also notice a slight fuel odor coming from the vehicle if this happens.

Causes of Code P0449

The code P0449 is typically triggered when an electrical problem in the circuit or a mechanical problem with the vent valve interferes with its operation. However, many other reasons can cause onboard diagnostics to trigger the P0449 code. Some common causes include:

  • Poor quality electrical connection
  • Damaged Powertrain Control Module (PCM) or Engine Control Unit (ECU)
  • Faulty vent valve solenoid
  • Damaged wiring harness
  • Defective or leaking fuel cap
  • Loose fuel tank filler
  • Restricted or blocked EVAP system vent path
  • Clogged PCV ventilation hose

How to Diagnose Error Code P0449? 

Doing diagnostics is a crucial part of fixing any car problem. You will not be able to fix the issue if you can’t find the cause of the problem. To diagnose the P0499 code or any other trouble code, you need to use an OBD-II scanner. Let’s get started!

Step-by-Step Guide

  • Using a scanner to check for any diagnostic trouble code stored in the ECU
  • Save the freeze frame data associated with the codes. Review the history and pending codes, as this will         give you an idea of your vehicle's condition before the code is set.
  • Clears all of the codes.
  • Perform a driving test to confirm any symptoms that are present.
  • Inspect the wiring harness and the vent valve and look for any damage.
  • Use an advanced scan tool to operate the EVAP functions. This is to verify if there is a malfunction with           the vent valve.
  • Checks for continuity between the vent wiring and ECU.
  • Perform a test on the ECU.

How to Fix Code P0449

After diagnosing, you may probably know where to start repairing. Here are some of the possible fixes:

  • Check the fuel cap and make sure it is on tight and doesn't have any cracks
  • Reprogram the ECU with updated software
  • If the cause of P0449 was a defective vent valve, replace the charcoal canister vent valve. 
  • If there was a wiring issue, fixing that may be all that's necessary. However, if further diagnosis finds an         issue with the ECU, repairs will likely be more extensive and costly.
  • If the issue comes from faulty electrical connections, it's important to clean all the contacts and ensure           they are properly seated.
  • Replacing the ECU is likely your last resort and can be very costly.

Common Mistakes When Diagnosing the P0449 Code

It's important to make sure that you check all of the possible causes and symptoms to pinpoint the issue effectively. However, we cannot avoid making some mistakes while trying to clear this error code. Here are the common mistakes that people make when diagnosing:

  • Not checking all of the possible causes and symptoms
  • Not using an advanced diagnostic scanner to check the EVAP system
  • Not checking the wiring harness for damage
  • Not verifying that the vent valve is working
  • Replacing the vent valve without confirming the exact problem

Code P0449 FAQs

1. Is the P0449 Code Serious?

Anything that relates to emission control on a car should be taken seriously. While the P0449 code may not cause your vehicle to fail inspection, it still needs to be addressed as soon as possible. If you wait until you fix this, it may become a bigger problem and become even more expensive to have it repaired. 

2. What OBD scanner should I use to scan this code?

You should use an advanced diagnostic scanner to check the EVAP system for this code. This will allow you to see if there are any issues with the system and help you to diagnose the problem.

3. Can I diagnose the P0449 code on my own?

Yes, you can do it yourself as long as you know what you are doing. If you are not comfortable doing this yourself, you can take your vehicle to a mechanic for diagnosis and repair.

4. Will making the wrong diagnosis harm my car?

Yes, a wrong diagnosis can cause further damage to your car. If you are unsure what is causing the P0449 code and you have enough budget, take your car to a mechanic for diagnosis.

5. Can I drive with the code P0449 still present?

Yes, you can drive with the code P0449. However, it is not recommended to do so, as the issue causing the code may get worse over time.


The code P0449 can be caused by many things, including a faulty sensor or the vent control valve issue. But don't worry as there are several solutions as well! By following the steps in this guide, you should be able to diagnose and fix the problem yourself without taking your car to a mechanic.

Hopefully, this guide provides you with enough information to get started on fixing your P0449 code. Always consult a professional if you're not confident in performing these repairs yourself.