P0442 – Meaning, Causes, Symptoms, & Fixes

Code P0442 Definition

Evaporative emission control system leak (medium).

Code P0442 Meaning

The evaporative emission control (EVAP) system prevents fuel vapors from escaping into the atmosphere. The fuel vapors from the fuel tank are absorbed and stored by charcoal pellets in the charcoal canister. The vent control valve is controlled by the engine control module (ECM) and allows air to flow into the charcoal canister to purge the gas vapors into the engine air intake to be burned. The flow of the gas vapors from the charcoal canister to the engine air intake is controlled by a purge valve. Both the vent control valve and the purge valve are usually open when the engine is at normal operating temperature. However, the ECM occasionally performs leak tests to ensure the evaporative emission control system is working properly. During the leak test, the ECM closes the vent control valve and purge valve to create a vacuum. If the EVAP system does not maintain the pressure, the ECM recognizes an evaporative emission control leak. In the case of P0442, it is a medium sized leak, between .020”-.040” in diameter.

P0442 Symptoms

  • Check Engine Light is on
  • Decreased fuel economy
  • Fuel smell

P0442 Causes

  • Loose or damaged gas cap
  • Leaking or disconnected EVAP hose
  • Faulty purge valve
  • Faulty canister vent valve
  • Charcoal canister leak
  • Leaking fuel tank

Code P0442 Severity – Low    

It is unlikely the driver will notice any symptoms with check engine light code P0442 other than a slight odor of fuel, decreased fuel economy, and the check engine light. However, as with all check engine lights, it is recommended that you get it fixed as soon as possible so the engine can be running at the proper specifications to prevent further damage.

Code P0442 Common Diagnosis Mistakes

Many assume that a loose fuel cap is the only problem and do not perform all the tests necessary to diagnose the full EVAP system. The P0442 small leak is a bit trickier to diagnose. Also, many manufactures have technical service bulletins regarding EVAP codes. Be sure to check if your vehicle has any technical service bulletins available to save time diagnosing and or misdiagnosing the car.

Code P0442 Diagnosis Steps

How To Diagnose P0442

  1. Scan your vehicle to verify P0442 is the only code present. If other codes are present regarding fuel pressure or the fuel system, repair and diagnose those first.
    1. If it is paired with P0441, P0440, and/or P0446 there is most likely a solenoid failure, leaking charcoal canister, or a more complex EVAP leak.
  2. Inspect your gas cap to see if it is loose or damaged
    1. If your gas cap is loose, tighten it and clear the code.
    2. Inspect your gas cap for physical damage or deterioration. However, it should be noted that damage to the gas cap or deterioration of its components are not always noticeable. If your gas cap was not loose and you do not see any indications of failure, try replacing the gas cap anyways and clearing the codes. Gas caps are relatively inexpensive and are often the fix for code P0442.
  3. Check for cracked or disconnected EVAP hoses near or connected to engine air box
    1. Replace cracked/disconnected hoses
    2. Clear code
  4. Inspect the fuel tank and charcoal canister for damage and leaks. Replace if necessary.
  5. Check both the charcoal canister vent valve and purge valve for proper operation. These valves can get sticky causing leaks or the internal solenoid can fail and not operate. To test:
    1. Disconnect the valve connector and test that the valve is receiving power with a multimeter
      1. If there is no power, there is most likely a wiring problem or a faulty powertrain control module.
      2. Tech Tip- The canister vent valve is usually located under the car in the rear of vehicle by or attached to the charcoal canister. The purge valves are usually under the hood near the airbox or intake manifold.
  6. The leak causing code P0442 is often too small to see. If you have completed all of these diagnostic steps, a smoke test may be necessary. You can purchase a smoke tester from Amazon to do it yourself, or you may want to take it to a shop to find the leak.
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Comments 21

Mary Salluce

June 23, 2018

I am debating on whether to look for a new car toward the end of the year, depending on how expensive the emissions repair will be. My 2000 Malibu will not pass inspection this July. Where can I get the repair done at reasonable price, please?
Thank you

FIXD Marketing

June 25, 2018

Hi Mary!

You can actually use the FIXD app to look for a repair shop near you!

Alan

June 26, 2018

How can I turn off the check engine light?

FIXD Marketing

June 28, 2018

Hi Alan,

Our sensor (FIXD) connects to an app on your phone and allows you to learn more about your Check Engine Light, provides an explanation of your trouble code in simple and understandable terms, and also gives you the ability to turn your Check Engine Light off.

David Curtis

July 15, 2018

How do I turn off the engine light

FIXD Marketing

July 25, 2018

Hi David,

You are able to clear your Check Engine Light with the FIXD OBD-ii sensor and the FIXD mobile application!

The FIXD Team

Tara elkins

October 14, 2018

Hi Team, we had a lot of work done on our car two days ago. It all had to do with the axels, tie rods, hub barrens, radiator replaced, etc. could this have caused damage to make the Check engine light come on?

Phillip dyson

November 3, 2018

How do I turn the check engine lift off and what is the cost to repair?

Mark McGahey

June 27, 2018

My 2018 GMC Canyon has the P0442 indication which implies a loose gas cap but it doe not have a gas cap? It only has 700 + miles.

FIXD Marketing

July 9, 2018

Hi Mark,

The usual fix for trouble code P0442 is a loose or damaged gas cap but there are other possibilities as well. You may need to run a few tests to pinpoint the problem.

The FIXD Team

Audrey

September 15, 2018

Hello. I had the problem fixed in July and the check engine light is back on again. Should they charge me again for the same problem?

Zeke

August 1, 2018

Using FIXD, code 0442. Is there anyway to find out if any of the components of the Evap system is malfunctioning just by looking in the information given by FIXD when communicating with car computer?

FIXD Marketing

August 3, 2018

Hi Zeke,

It is possible to monitor the tank pressure to confirm if a leak is present or not. This will be dependent on your vehicle specific repair manual on what this value should be. Let us know if you find the issue!

The FIXD Team

Phillip dyson

November 3, 2018

How do I repair?

Dale

September 3, 2018

If I clear this code and a problem still exists, will the check engine light come back on?

Mark

September 7, 2018

Yes, it may take a day or two but if the issue isn’t resolved the check engine light will turn back on!

Danny Watkins

October 11, 2018

Yes

Dale

September 3, 2018

If I clear this code, and a problem still exists, will the check engine light come back on?

Henry Holody

September 24, 2018

Yes, after about 125 miles of driving.

Jennifer

October 9, 2018

I don’t see in the app a place to clear the code. Can you explain where this is in the app please

FIXD Marketing

October 11, 2018

Hey Jenifer!
Try hitting the Diagnostic Report button after scanning for codes. Once that page is done loading, there should be an option at the bottom of the page to clear the codes. Be sure not to try and clear just one specific code, but actually all of the codes that have come up.

FIXD Team