What is P0449 DTC? Common Symptoms, Causes, and Solution
With time, the fuel cap can become loose or other issues can result in the evaporation of the fuel fumes. But do not worry, as the OBDII module will send a signal to ECU to illuminate the warning light so you can resolve the issue promptly.
The following are the key takeaways from this article:
P0449 is a low-intensity DTC indicating an error in the evaporative emission control system vent valve.
The common causes of this engine fault code include a damaged tank filler cap, damaged fuel tank, damaged EVAP canister valve, damaged carbon canister, and damaged evaporation hose.
The common symptoms of this DTC include a decrease in the fuel economy, a check engine light on the vehicle’s dashboard, a gasoline odor, and a rough engine start.
The solution for this DTC includes resetting the DTC, replacing the faulty gas cap, replacing the EVAP line, and replacing the vacuum control system solenoid.
The cost to resolve this issue can range between $20 and 600, depending upon the extent of the issue.
Introduction
Some issues are not evident while driving. However, the ECU recognizes the P0449 issue and illuminates the warning light.
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One such engine fault code is P0449, a low-intensity code illustrating that the evaporative emission control system vent valve has a malfunction.
This engine fault code has no clear symptoms, such as low engine power or a shaky car while accelerating. Yet, the ECU will get a signal about this malfunction (3). This article will further illustrate the symptoms, causes, and solutions to resolve P0449 DTC.
Role of EVAP in the Vehicle
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The car’s EVAP functions to capture the raw fuel evaporating from the fuel system. EVAP collects the raw fuel from the filler neck, tank, or anywhere in the fuel system.
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Then the ECU dictates the EVAP to send the fuel vapors according to the combustion speed, load, and temperature. EVAP has become a major requirement for gasoline vehicles since the 1970s (1). A typical EVAP comprises of vapor storage canister, valves, hoses, and a sealed fuel tank. Suppose there is no EVAP in the vehicle. In that case, there is a possibility that the fumes will evaporate directly into the air resulting in increased air pollution. Further, the EVAP also comprises a carbon canister that can store fuel vapors (1). This carbon canister also has a vent valve that allows the air to enter the system, storing and purging the air-fuel mixture according to the engine’s requirement.
How to Read P0449
The following table has read every character of P0449 DTC (2):
Number of Character
Specific Character
What does it Signify
First
P
The problem lies within the powertrain part of the vehicle. This means that the engine, transmission, or fuel system can malfunction.
Second
0
This means that the code is standardized, so the SAE manual can be used further to interpret the code instead of the instruction manual.
Third
4
This number illustrates that the problem lies within the vehicle’s emission system.
Fourth and Fifth
49
The specific fault index is 49, indicating an error in the evaporative vent valve.
P0449 means that the DTC code is an SAE-standardized code, and the problem lies within the vehicle’s emission system. Furthermore, the third, fourth, and fifth characters illustrate an error in the evaporative vent valve, indicating an error in the vehicle.
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Causes of P0449 DTC
The following are the causes of P0449:
Damaged Tank Filler Cap and Damaged Tank
For better engine performance, the tank filler cap must be tightened properly. Otherwise, dirt and debris will enter the tank, impacting the fuel’s overall efficiency .
Due to the loosened or damaged tank filler cap, the engine code P0049 indicates an error with the evaporation system of the engine.
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Due to the damaged tank filler cap, the fuel vapors will escape from the tank, generating multiple problems for the emission system (1). Also, the dirt and debris will be deposited in the fuel tank, ultimately damaging the fuel injectors. Due to this, the vehicle will fail to accelerate at high speed, and the engine’s performance will become rough and idle.
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Other than it, there is a chance that engine code P0449 is indicated due to the damaged tank system. The leakage in the fuel tank system will generate problems as the leaked gasoline will leak under the car’s rear end, and the gasoline smell will spread around.
The engine code is indicated to avoid accidents, and the check engine light is illuminated.
Damaged EVAP Canister Vent Control Valve
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Another major reason for the engine code P0449 is the damaged evaporation control valve. The vapor vent control valve consists of the solenoid, and the purpose of this system is to store the fuel fumes in the vacuum line.
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This valve is operated electrically, and this valve system opens after certain intervals to release the fuel vapors in the manifold for the combustion process—this help in starting the engine. However, suppose the electrical connection between these vent valves is weak. In that case, the fumes will not enter the system on time, and the combustion process will be slowed down (1). This will ultimately impact the engine’s performance, making it difficult to start the vehicle because the combustion process is delayed as wrong information is sent to the electrical control unit due to poor electrical connections.
Defected Carbon Canister and Damaged Evaporation Hose
The carbon canister plays a fruitful role in the evaporation Emission system, and this system does not allow the release of harmful fuel chemicals into the air. Rather they utilize these harmful substances to power up the engine system (5).
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The carbon canister can get damaged if a large amount of fuel enters the system. In addition, it will create multiple issues, such as limiting engine performance and increasing emissions, which triggers the engine code P0449.
Also, due to the defective evaporation hose, the required amount of pressure must be generated. As a result, the engine’s efficiency is impacted, and engine code P0449 is indicated.
Symptoms of P0449 DTC
The following are the symptoms of P0449 DTC:
Decrease in the Fuel Economy and Check Engine Light
The most common symptom of the engine code P0449 is the indicated engine light. The engine light on the dashboard is illuminated due to various reasons, such as weak electrical connections between the sensor, damaged sensors, a defective carbon canister, and an evaporation hose.
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This engine light indicates that there is an error in the evaporation system of the engine. Also, the fuel economy is reduced due to the dirty fuel injector, and fuel needs to be supplied to the cylinders properly (2). This makes the engine’s performance weak, and as a result, engine code P0449 is illuminated.
Gasoline Odor
The other symptom of engine code P0449 is the gasoline smell. The bad odor from the engine is released due to the poor evaporation system.
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The gasoline smells released from the exhaust system due to the missing fuel cap or the leaking tank (3). The vapors from the emission system are released into the air. Thus due to the loosened cap, the pressure in the engine is not maintained, and as a result, the engine’s performance becomes poor. Also, the gasoline odor is observed because of the gas leakage in the system. Gas leaks usually occur due to the damaged fuel lines and puddles created beneath the car system. Thus, the gasoline odor is the major symptom of engine code P0449.
Rough and Idle Engine
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The engine also becomes rough and idle due to the weak evaporation and emission system. In addition, dirt and debris are deposited in the fuel tank due to the loosened cap. Thus, the fuel injectors become blocked, and fuel is not dispersed in the cylinders at an accurate time.
This poorly affects the performance of the engine. In addition, weak electrical connectivity issues and defective carbon canisters cause emission issues and engine noise (1). This rough and poor engine performance is the major symptom of engine code P0449. However, this symptom appears much less in vehicles with P0449 DTC.
Solutions of P0449 DTC
Following are a few common solutions of P0449 DTC:
Reset the DTC and Test Drive
The first solution to this engine fault code is to reset the DTC and test drive the vehicle. In some cases, the ECU might face an error that will send the wrong signal to the car’s OBDII and cluster meter. In this case, the DTC will occur without any actual error. So, connect the hand-code reader with the OBDII module and try resetting the DTC. After resetting the DTC, test drives the vehicle to ensure that the warning sign does not appear again. In case the warning sign appears again, it is better to figure out the root cause of the issue.
Replace Gas Cap
The common solution of P0449 DTC is to replace the gas cap. The gas cap of a typical car is located inside the fuel door at the backside. However, the location of the fuel door can change depending on the model, make, and car variant (5). An easy check for a faulty gas cap is to check its ‘O-seal.’ An O-seal can wear when the gas cap is removed and tightened while refilling the fuel (2). The gas cap of common car models is available on eCommerce platforms. However, suppose you own an out-of-market car model. In that case, the fuel cap is not available easily, and you might have to order the fuel cap from the manufacturer.
Replace the EVAP Line
EVAP lines can deteriorate over time due to engine vibration and heat. This will cause the rubber lining to collapse or fall off the vacuum system, impacting the connection with a solenoid. You can start your inspection by checking for crackups and tears up to the vacuum control solenoid. This solenoid is either mounted on the intake fold or near the fender well of your vehicle (5). This EVAP line can be easily replaced at home, but ensure that you have ordered the rubber lining according to the model of your vehicle.
Replace the Vacuum Control Solenoid
Replacing the vacuum solenoid can be another solution to this DTC. To replace the vacuum solenoid, remove the solenoid. It opens or closes with each command. You can remove the solenoid and test it by grounding it and supplying a 12V power supply. If there is no click in the solenoid even after supplying the power, then the solenoid has gone bad and needs to be replaced. You can replace the solenoid by yourself or take the car to a professional mechanic to get it replaced.
Cost to Resolve the DTC
The following table illustrates the cost required to resolve P0449 DTC:
Common Issues
Critical Level
Cost Required to Resolve the Issue
Damaged Tank Filler Cap
Low: You can drive for long distances with this problem. However, there will be a decrease in the fuel economy as the fuel will evaporate when the cap is loose.
$20-70, depending upon the model of the vehicle, to replace the fuel cap.
Damaged Tank
Intermediate: It is risky to drive with a damaged tank, as leaking fuel can cause a fire in the vehicle.
$400-600 to replace the damaged fuel tank.
EVAP Canister
Low: There are no driving risks, but the car would not pass the emission tests with damaged components.
$150-400 to replace the faulty EVAP Canister.
Carbon Canisters
Low: You can drive for long distances with this problem. However, there will be a decrease in the fuel economy as the fuel will evaporate when carbon canisters are damaged.
$150-600 to replace the carbon canister.
Defected evaporation hose
Low
$150-600 to replace the entire EVAP system of the vehicle depending upon the model.
Labor Cost
–
$20-200 to replace the faulty components.
Conclusion
To conclude, P0449 is a low-intensity engine fault code that indicates an error in the evaporative vent valve. This can occur due to loose gas caps and different problems in the EVAP system. In addition, the defective evaporation hose and carbon canisters can also cause the OBDII to send this code to the ECU. So, suppose you are experiencing a decline in the car’s fuel average or smelling a fuel odor. In that case, there is a chance that the evaporative vent valve is malfunctioning and might need repair.
P0449 is not a serious DTC, and you can drive your car for as long as possible. However, you might notice a decline in the fuel average. The damaged tank can also mean that your fuel is leaking during driving. This is a dangerous situation as it can sometimes ignite a fire.
Generally, suppose the fuel cap is loosened. In that case, the ECU will detect fuel evaporation and light up a warning signal on the vehicle’s dashboard. Similarly, the drivers can detect a loosened fuel cap as they can rotate the fuel cap and check its tightness. Generally, the O-seal on the fuel cap is damaged, which can be seen visually. Therefore, you are recommended to replace the fuel cap when it loosens.
EVAP malfunction can be detected by a rapid decrease in the vehicle’s fuel economy. Similarly, you will also smell fuel smell from the standing vehicle. This is a sign that the EVAP is malfunctioning and needs replacement shortly.
