Emission Control System Malfunction (Here Is How To Fix)

emission control system malfunction

‍Have you ever wondered what emission control system malfunction means and how to fix that? Well, we got you covered.

The Evaporative Emission Control System (EVAP) is a crucial component in modern vehicles, designed to prevent harmful fuel vapors from escaping into the atmosphere.

It is regulated by various local and federal agencies, including the Environmental Protection Agency (EPA), to ensure it functions efficiently and protects public health.

A malfunction in this system can trigger a Check Engine Light and result in error code P0440, indicating an issue with one or more parts of the control system.

Here are a few steps you need to take to fix the emission control system malfunction, which includes:

Step 1: Check the Gas Cap

Step 2: Inspect EVAP Components

Step 3: Check for Leaks in the EVAP System

Step 4: Seek Professional Help

In this article, we will discuss the symptoms, causes, and solutions to fix the P0440 code and related emissions problems.

Understanding the Evaporative Emission Control System

The EVAP system comprises several components that work together to capture, store, and purge fuel vapors.

These components include the fuel fill cap, vapor recirculation tube, fuel tank vapor control valve, evaporative emission canister, fuel tank pressure sensor, canister vent valve, evaporative two-way valve, and the evaporative canister purge valve.

When functioning correctly, the EVAP system prevents fuel vapors from escaping into the environment and maintains pressure within the fuel system.

Can I Drive with Emission Problem?

I would not recommend driving with an emission problem as it could cause further damage to your vehicle. It’s best to bring your car to a certified mechanic for prompt diagnosis and repair.

Additionally, a diagnostic scan can alert you to upcoming service and maintenance tasks depending on the vehicle’s mileage and driving.

In most cases, a diagnostic test costs less than $100 and can be completed within an hour [3]. RepairPal and AutoMD are useful resources that can help estimate repair costs. BMW diagnostics tools such as the Carly app can also help estimate repair costs.

How Much Does It Cost to Repair the Emission Control System?

On average, the emission control system fault will cost from $44 to $56 to fix. However, the cost of repairing the emission control system can vary depending on the make and model of the car and the extent of the damage.

For instance, replacing a catalytic converter on a Honda Pilot 2006 can cost around $1,240-$1,536 according to AutoMD. Similarly, replacing an O2 sensor can cost around $221-$278 according to OEM Ford Parts.

It’s recommended to bring the car to a certified mechanic for diagnosis and repair to get an accurate estimate of the cost.

Symptoms of a P0440 Error Code

A P0440 error code indicates a general issue with the EVAP system, which could result from a number of failures, including:

  • Gas Cap
  • Purge Valve or Vent Valve
  • Leaking Charcoal Canister
  • Leaking EVAP Hoses
  • Fuel Tank Pressure Sensor

Although a significant vapor leak may not cause noticeable changes in vehicle performance, the Check Engine Light will be triggered, and an OBD-II scanner will read the P0440 error code.

Fuel vapor leaks can be hazardous, so it is essential to inspect the EVAP system even if you do not experience performance issues.

Causes of P0440 Error Code

Several factors can cause a fuel vapor leak, and you will need to inspect each part to determine the solution.

Some solutions are relatively straightforward, such as checking for a loose gas cap or replacing a damaged component. However, if the issue persists, more complex repairs may be necessary.

Fixing P0440 Codes

Step 1: Check the Gas Cap

The most common cause of a P0440 code is a loose or damaged gas cap. Ensure the gas cap is securely tightened and inspect it for any signs of damage or deterioration. If the gas cap is not the issue, consider replacing it as a simple and cost-effective solution.

Step 2: Inspect EVAP Components

Examine other EVAP components, such as rubber or plastic hoses, purge and vent valves, charcoal filters, and charcoal canisters. A faulty or malfunctioning purge or vent valve could be the cause of the P0440 code.

Step 3: Check for Leaks in the EVAP System

A more complex solution involves checking for small cuts or holes in the EVAP system hoses or tubing. A tiny cut could cause a large enough vapor leak to trigger the P0440 code.

Carefully inspect the entire length of fuel lines and hoses to identify any leaks, or consider using a professional smoke machine to detect leaks more efficiently.

Step 4: Seek Professional Help

If the issue persists after trying the steps above, it may be necessary to consult a professional mechanic or a certified auto repair shop.

They can conduct a thorough diagnostic check to identify the cause of the P0440 code and recommend the appropriate repairs.

Preventative Maintenance and Repairs for European Automobiles

European automobiles, such as those serviced by Lucas Auto Care in Cypress, TX, are known for their precision engineering and high performance.

However, they are not immune to emissions problems, including those related to the EVAP system. Regular preventative maintenance can help identify potential issues and ensure your vehicle remains in optimal condition.

Common Mistakes in Diagnosing P0440 Code

One of the most common mistakes in diagnosing a P0440 code is assuming the gas cap is the only issue without thoroughly examining the entire system.

Another common mistake is neglecting to ask the vehicle owner if the gas cap was recently left loose or not tightened properly.

Severity and Consequences of P0440 Code

A P0440 code may not cause immediate harm to your vehicle, but it can result in a failed emissions test and potential damage to the emission system over time. Fuel vapor leaks can also pose health risks and environmental concerns.

Therefore, it is essential to address the issue promptly to maintain your vehicle’s performance and safety.

Repair Costs for P0440 Code

Repair costs for a P0440 code can vary depending on the specific issue and the required repairs. Some potential repair costs include:

  • Gas Cap: 60
  • EVAP Line: 100
  • EVAP Vent Control Valve: 200
  • Purge Volume Control Valve: 200

How long can you drive with the emissions light on?

If the light is the only issue and the car is running smoothly, it is generally safe to drive. However, it is important to address the underlying issue as soon as possible to avoid any potential damage to the vehicle’s emissions control system.

A driver can safely drive up to 100 miles to a repair shop if the light is steady and there are no other signs of engine trouble.

Where is the emission control system located?

The location of the emission control system components can vary depending on the make and model of the car, but they are typically located in the engine compartment or underneath the vehicle.

Some common components of the system include the air regulator, cold start valve, pressure regulator, injector, thermotime switch, spark delay valve, and air flow sensor.

If you are looking for the location of a specific component, such as the pressure sensor for code P0451 on a 2009 F150 4.6, it is recommended to bring your vehicle to a certified mechanic for a proper diagnosis.

What Does Check Emission System Mean? (How to Fix and Reset) >> Check out the video below:


Understanding the importance of the EVAP system and the consequences of a P0440 error code is crucial for maintaining your vehicle’s performance and safety.

By conducting regular inspections and preventative maintenance, you can minimize the risk of emissions problems and ensure your vehicle remains in optimal condition.

If you encounter a P0440 code, follow the steps outlined above and consult a professional mechanic or certified auto repair shop if necessary.

Stephan K.

I have been working as a mechanic for over 13 years and have been deeper into advanced automotive diagnostics for some years.

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