OBD2 Code P0440: Causes, Symptoms, Diagnosing & Fixes

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How to fix P0440 obd2 code?
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Having a vehicle with OBD2, you must have faced issues with the codes. What do they mean? How do diagnose and fix issues? We have created a helpful guide on how to fix the p0440 OBD2 code error.

OBD2 Code P0440; What is it and what does it indicate?

OBD2 Code P0440; What is it and what does it indicate?

When the OBD2 detects a problem with the Evaporative Emission Control System (EVAP) system, the P0440 error code appears. It would be suggesting a malfunctioning EVAP control system component. The EVAP system components include the gas cap, gasoline lines, carbon canister, purge valve, and other hoses. 

What does the EVAP system do?

This system prevents fuel vapors from leaving the vehicle. The fuel vapors travel through the hose to the charcoal canister for storage. When the engine is turned on, the purge control valve opens and allows the intake vacuum to pull fuel vapors into the engine. 

OBD2 P0440; Causes

If you are having trouble with a p0440 code error, it is better to look for certain things that can be creating problems in the EVAP system, for instance;

  • Poor, faulty, or damaged gas cap installation
  • Purge solenoid failure 
  • Unplugged or short canister might be the issue
  • Leaking or disconnected EVAP hose 
  • Fault in the purge valve
  • Canister vent valve damage/leak
  • Leakage in the charcoal canister
  • Leaking fuel tank

OBD2 P0440 Error; Symptoms

Remember that when your car’s ECM/PCM system detects a significant leak in the EVAP system, the code is set. Nevertheless, this does not always imply the presence of a leak. For quick diagnosis here are some of the symptoms you should keep an eye on for p0440 error. 

There are a few instances in which you may notice a strong odor of gasoline in the passenger compartment. It happens because of the leak in the EVAP system that diminishes the system’s ability to contain gasoline odors.

People with previous experience or professional drivers will become aware of the problem when the check engine light illuminates. However, the problem should not be ignored as it can lead to the emission of harmful pollutants into the atmosphere.


To diagnose the po440 problem code, you should do the following steps:

  • Firstly, scan the codes and document them in the ECM.
  • To determine when the issue happened, examine the freeze frame data.
  • From the front to the back of the car, inspect the complete fuel system, including the fuel lines and vapor lines, for any evidence of gasoline or vapors leaking.
  • Check to make sure the gasoline cap isn’t loose, since this is the most prevalent issue.
  • A smoke leakage test should be done using the test vapor port on the fuel vapor system. It helps in pinpointing the source of the vapor leak.

If you find no leaks, use the manufacturer’s pinpoint test to thoroughly inspect the vapor sensor and system for this code, as these systems can vary greatly across manufacturers.

Mistakes To Avoid While Diagnosing OBD P0 Error

As the code P0440 error leads to potential causes of the major issue. Therefore, to ensure accuracy, it is better not to assume that the only reason can be a leaking gas cap. Changing the gas cap can be applied to numerous instances. However, doing a proper checkup of relevant issues can help you save time and money, treating the actual cause. 

How To Fix p0440 Code Error

How To Fix p0440 Code Error

The code P0440 can be stored for several reasons. Therefore, there is no one “magic” remedy for the problem. There is a possibility that you see this or a comparable code if you have left the gas cap off or loose. As a result, be certain of where the problem lies. 

To repair the p0440 OBD2 error code, here are various methods you can use, for instance;

  • You must visually examine the EVAP system for cuts or holes in the tubes or hoses before use.
  • Check the area around the EVAP purge solenoid for any broken or disconnected hoses with care.
  • Replace the malfunctioning sensor.
  • Inspect the purge valve for any damage.
  • Ensure that the fuel cap is properly tightened or reset.
  • Repair a leaky fuel cap with a poor seal or any vent.
  • It is necessary to repair or replace any leaking vapor system components, such as a vapor control valve or a carbon canister, immediately.

Additionally, if you are not sure of what step to take or unable to understand how it works, it is better to consult your vehicle’s manufacturer repair documentation. It comes with all the information on diagnosing and correcting diagnostic issue codes. Moreover, the particular repair techniques for a P0440 can vary depending on the make and model of your vehicle.

Vehicles that usually face P0440 issues:


What is the approximate cost of repairing P0440?

You can expect a minimum of $100 diagnostic price to properly diagnose the problem. The cost of repair, on the other hand, might greatly vary depending on factors like what is discovered, the type, and the model of the vehicle. However, most automobiles have a rubber hose in their system that can be changed for less than $100 in materials and labor.

Is it safe to drive with the P0440 error code?

Even though code P0440 will not create any visible driving concerns, it will cause an emission test to fail. However, like with other diagnostic issue codes associated with the check engine light, you should get it repaired as quickly as possible to restore the normal functionality of the vehicle.

What is the location of the EVAP sensor?

Evaporative emission (EVAP) pressure sensors, also referred to as Fuel Tank Pressure (FTP) sensors, are devices that monitor air pressure or vacuum in the evaporative emission (EVAP) system. This sensor is often located on top of or inside of the gasoline tank, depending on the model and type of the vehicle.