Causes, Symptoms, Severity and Cost

Technical Description:

A general problem with the vehicle’s Evaporative Emission System.

What P0440 really means:

The Evaporative Emission System in a vehicle manages the gasoline vapor that builds up in the tank through a system of collection into a charcoal canister, that will eventually discharge to the engine to be burned. Federal emission standards seeks to reduce the amount of gasoline vapor (hydrocarbons) leaked from a poorly sealed tank into the environment. The system is checked periodically by the computer for very minute leaks - usually .010” to .040” in size. This code is usually accompanied with a P0441, P0447, P0456 et. al., which further identifies and localizes the issue.

What are the symptoms of a P0440 code?

Do not fear, this does not mean that your car has fuel pouring or even dripping from the tank. This emission system is not looking for liquid leaks, and even though your gas tank may have small vapor leaks if it’s very old, the most likely culprits are rubber hoses or motorized vents which route the vapors to storage and then to the engine. For most of the driving population, these small vapor leaks go unnoticed - they do not effect performance or fuel economy.

What is the severity of a P0440 code?

Minor. Repairs should be planned to correct the problem, but there is no immediate danger of the car breaking down or performing poorly.

What repair(s) are needed to resolve a P0440 code?

Rubber hose or motorized vent (exhaust system): Repairs should be planned to correct the problem, but there is no immediate danger of the car breaking down or performing poorly. Schedule a convenient appointment and expect to drop off the car for at least the day to be diagnosed and repaired. These small leaks or broken valves take time and patience to find.

What is the cost to resolve a P0440 code?

  • Estimated diagnosis cost: $100
  • Estimated part(s) and labor cost: Under $100 - ? (pending repair needed)

Expect to pay a diagnostic fee of $100 minimum for a shop to diagnose the problem. However, the repair cost can really vary depending on what is found to be wrong and the type of car. A rubber hose in the system for most cars may be replaced for under $100 parts and labor. If any of the valves, the storage container, or the fuel tank (including the filler neck) are found to be leaking then the price can really climb. Many of the parts in this emission system are only available from the dealer.

Keep in mind, pricing will vary by location and your vehicle make and model. If you don't already, save time and money by using Openbay to compare pricing and book an appointment with a service center in your area.

Service article written by an ASE Master Technician

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