P0442: Evaporative Emission System Leak Detected (small leak)

If you’ve got the P0442 error code showing up on your OBD scanner, don’t worry, as it is easily fixable.

Here is a quick brief to let you know what you’re facing and what to expect.

  • P0442 Definition: Evaporative Emission Control System Leak Detected (Small Leak).
  • Code Type: Generic – P0442 indicates the same problem whether you’re having a Chevy, Ford, or Toyota, etc.
  • Can I drive with the P0442 code? Yes. There is almost no danger to the driver.
  • Easy to fix: Beginner to intermediate DIY skills.
  • Cost: $10 – $20 (common)

Luckily, P0442 is safe to drive with!

But to avoid more harm to the car’s fuel economy and environment, let’s read on to know the possible causes, how to fix the issues, and the replacement costs.

What Does The P0442 Code Mean?

P0442 is an OBD-II generic code triggered when the engine control unit (ECU) detects a fuel vapor leak (small) somewhere in the evaporative emission control (EVAP) system.

The EVAP is a closed system, consisting of several valves, lines, and a charcoal canister.

Its purpose is to help prevent any fuel vapors from escaping into the atmosphere. 

evap system
The fuel vapors can be stored in the charcoal canister and will be sent to the engine for combustion.

What happens if there is any leak in the EVAP system?

If there are any EVAP leaks, the fuel odor can enter the car’s interior and cause performance issues, triggering P0442. 

You can continue to drive your car in the short run, but it’ll negatively affect the car’s mileage and the environment. 

p0442 causes, symptoms and how to fix

P0442 Causes Identification: Quick View

The EVAP system is built around several components, and most of the leaks are hard to detect as they could be present in any of these parts. 

The table below will help identify possible causes for the leaks and their solutions.

Codes CombinationCausesSolutions
Only P0442Loose and faulty gas cap.

Cracked or disconnected EVAP lines.
Tighten or replace the gas cap.

Use a smoke test to identify the leak and replace the EVAP lines.
P0442 + P0457Loose and faulty gas cap.Tighten or replace the gas cap.
P0442 + P0455Leak in the charcoal canister.

Leak in the fuel tank.
Replace the charcoal canister.

Replace the fuel tank.
P0442 +P0446Failed EVAP vent.Replace EVAP vent.
P0442 + P0441/P0443/P0445Failed EVAP purge valve.Replace the EVAP purge valve.

Note: The causes for each code combination are the most common ones. There can be some uncommon issues hidden under those codes.

P0442: Causes, Symptoms, And How To Fix

It is important to understand what is causing the underlying problem to determine a solution. 

Let’s look at some of the common causes of the P0442 error code and how you may go about fixing them. 

Cause #1: Loose Or Faulty Gas Cap

Check your car’s gas cap first before moving on to further diagnosis.

Although a fuel cap may look pretty simple, it does play a vital role in preventing dirt, dust, and other particles from entering the fuel tank. The gas cap also acts as a seal, stopping the fuel vapors from escaping. 

A faulty gas cap can cause the fuel vapors to leak into the atmosphere, resulting in the illuminated check engine light.

Cause #2: Cracked Or Disconnected EVAP Lines

You may be seeing the P0442 error code because of cracked or disconnected EVAP lines. 

A running car can experience certain vibrations, causing the EVAP hose to disconnect and trigger the P0442 fault code. 

On the other hand, cracked hoses are not so common as they’re not exposed to excessive heat. However, it can experience wear and tear due to age.

Symptoms of a faulty/disconnected EVAP line include:

  • P0442 error code.
  • Check engine light on.
  • Poor engine performance.
  • Hard start.
  • Failed emissions test.

Check for any disconnected EVAP lines. If there are any, make sure to reconnect the lines and replace the clamps that hold the hoses in place.

However, it can be challenging to identify if you have a cracked EVAP line. You would need to conduct a smoke test to determine the leakage. 

After conducting a smoke test, watch this video from D&E In The Garage to know how to replace the EVAP lines.

Cause #3: Leak In The Charcoal Canister

The charcoal canister captures the fumes in the EVAP system, which is then used to power the car’s engine.

After years of use, a charcoal canister may start to leak due to wear and tear, and if that occurs, it may cause the following symptoms:

  • Combination of P0442 and P0455 error codes.
  • Check engine light on.
  • Failed emissions test.
  • Reduced vehicle performance.
  • Fuel smell coming from the vehicle.

A leaky charcoal canister can cause performance issues and require replacement. Buying a new one is relatively inexpensive. 

You can even carry out the job at home with basic DIY skills. It’s just a matter of disconnecting the hoses and electrical connectors, removing the canister, and reconnecting everything.

A super easy video for skilled DIYers about how to replace the charcoal canister by CarsNToys.

Cause #4: Leak In The Fuel Tank

A gas tank is a durable car component and is placed in a protective area. 

However, it can sustain damage from accidents or get punctured by road debris, resulting in a leak. 

Here are some common signs that your fuel tank is leaking:

  • Combination of P0442 and P0455 error codes.
  • Fuel smell coming from the vehicle.
  • A wet spot under the car.
  • High fuel consumption.

You can repair the gas tank by using epoxy putty on smaller leaks and welding on larger leaking spots. But before you start welding, empty the fuel tank of any fuel and vapors. 

It can often be a hassle to seal a fuel tank. It’s best to replace a leaky fuel tank with a new one.

Cause #5: Failed EVAP Vent

The vent assists the EVAP system by allowing air into the charcoal canister.

A faulty EVAP vent can prevent fresh air from entering the EVAP system, affecting its operations.

Some of the symptoms of a failed EVAP vent include:

  • Combination of P0442 and P0446 error codes.
  • Check engine light on.
  • Pressure in the gas tank.
  • Failed emissions test.

If your car has a failed EVAP vent, it’s time to buy a new one.

A useful video from 1A AUTO on how to replace EVAP vent. Check it out!

Cause #6: Failed EVAP Purge Valve

The EVAP purge valve is responsible for “purging” the EVAP system by acting as a switch that holds the fuel vapors in the charcoal canister and prevents them from leaking. 

A failed EVAP purge valve will negatively affect the car’s emission output levels, indicating an evaporative emission system leak.

If you have a bad EVAP purge valve, you may experience the following symptoms:

  • A combination of P0442 with either P0441/P0443/P0445. 
  • Rough idle.
  • Poor engine performance.
  • Difficulty starting.
  • Low fuel economy.
  • Check engine light on.

To fix this issue, purchase a new EVAP purge valve and replace it with the old one.

Watch this video from Dynamic Prepper to know the process of replacing the EVAP purge valve.

How Much Does It Cost To Fix P0442?

The most common cause of the P0442 is a faulty gas cap which can cost anywhere between $10 and $20, depending on your car’s make and model. 

Other causes can set you back up to $1000 if the fuel tank is the problem. Below, we’ve broken down the repair costs (DIY or mechanic) according to the solutions.

The Estimated Repair Cost Of P0442

Replace gas cap– DIY: $10 – $20
– Repair shop: not recommended
Replace EVAP lines– DIY: $8 – $15
– Repair shop: $60 – $65
Replace charcoal canister– DIY: $80 – $250
– Repair shop: $130 – $350
Replace fuel tank– DIY: $600 – $800
– Repair shop: more than $1000
Replace EVAP vent– DIY: $30 – $150
– Repair shop: $60 – $250
Replace EVAP purge valve– DIY: $35 – $100
– Repair shop: $85 – $220

Note: The data in this table is collected in June 2022. The actual price depends on many factors, such as your car’s make and year, mechanic’s rate, etc.

You Ask, I Answer

Although a small leak in the EVAP system is not dangerous to drive with a P0442 error code for the short term, it is best to get it fixed.

I would like to thank you for sticking with me to the end. 

If you have any questions or concerns about the error code P0442, please let me know in the comments section below, and I’ll try my best to answer your concerns.

See ya!

Read more: The 9 Best OBD2 Scanners for 2024: The Only Review You Need