P0442 Trouble Code Help & Fix - Schedule an Inspection Today

What is the P0442 Code?

P0442 is a diagnostic trouble code (DTC) that is seen when an evaporative emission system leak is detected. This code may be seen with other EVAP system codes.

The ECU carefully monitors the EVAP system for any leaks or irregularities, when a small leak is detected the ECU set a Check Engine Light to be displayed on the dashboard.

How Serious is the P0442 Code?

The P0442 generally has no adverse symptoms other than the Check Engine Light being present. When this code is seen, it means that the EVAP system is leaking fuel vapors into the atmosphere. A slight dip in fuel economy may be noticed with this code. It should be safe to drive with this code set, but it’s recommended to have the vehicle inspected at your next convenience.

What Causes the P0442 Code?

Here are a few common causes the P0442 code may set in your vehicle:

• Faulty or loose fuel cap
• EVAP system line leak
• Charcoal canister leak
• Fuel tank leak
• Failed vent or purge valve

How to Fix the P0442 Code

The most common ways to fix the P0442 code are as follows:

• Replacing the gas cap
• Replacing the fuel tank
• Replacing the charcoal canister
• Replacing the EVAP system lines
• Replacing the purge or vent valves

P0442 Code Signs & Symptoms

The following are two common symptoms associated with the P0442 code:

• The Check Engine Light being present on the dashboard.
• Some vehicles may exhibit a slight drop in gas mileage with the EVAP leak

How a P0442 Code Inspection Works at YourMechanic

A mobile mechanic in your area from YourMechanic will come to your vehicle at your convenience to perform a diagnostic and fix the P0442 code.

A mechanic will follow these general steps when diagnosing and fixing the P0442 code:

1. Hooks up a scan tool to the vehicle's DLC port and checks for any codes present
2. Examines the freeze frame data associated with the code which shows the circumstances that were present with the vehicle at the time of the malfunction
3. Clears the codes and test drives the vehicle
4. Performs a visual inspection of the EVAP system, looking for any obviously cracked or broken components, and loose or damaged EVAP lines
5. Checks for cracks in the fuel tank or charcoal canister
6. Inspects the gas cap for proper fitment and condition, then tests with a gas cap tester
7. Uses a scan tool to monitor tank pressure and confirm if a leak is present
8. Tests the EVAP system solenoids and valves with scan tool
9. Performs a smoke test on the EVAP system, looking for smoke that indicates a vapor leak

Avoiding Mistakes When Diagnosing

Qualified technicians should have little problem diagnosing P0442 as long as all steps are followed in the proper order and none are skipped.

Commonly, the gas cap is the cause of P0442, if the gas cap is overlooked it can waste time and energy diagnosing other components.

Final Considerations

Professional level tools make diagnosing the P0442 leak much easier and accurate. An advanced scan tool that allows access to live data and control of the EVAP system is very helpful when dealing with the P0442 code or any EVAP code in general.

Some vehicles have the ability to be commanded with the scan tool to test the EVAP system for proper operation of all components, and can be used to help isolate which part of the system the fault or leak lies.

Since they are fuel vapors, most of the EVAP leaks are much smaller than the eye can see. A smoke test is performed to find hard-to-detect fuel vapor leaks. This is done by using a specialized smoke machine that pressurizes the fuel system and adds smoke so that small leaks will be visible.

P0442 Code Inspection & Repair

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.