Engine Code p0442 Meaning, Causes, Fixes (4 Steps)

Has your vehicle recently set a p0442 fault code?

If so, you are in the right place!

In this PopularMechanic article you will learn:

  • What Does The p0442 Code Mean?
  • What Caused The p0442 code (Possible Symptoms)?
  • How To Diagnose An p0442 Code?

And Much More!

Engine Code p0442 Meaning, Causes, Fixes (4 Steps)

Though it is easy to assume that a check engine light spells a serious problem for your beloved ride, the truth isn’t always this dire.

In fact, fault code p0442 is one of the most commonly encountered of all diagnostic trouble codes, and often one of the most easily fixed.

With a little simple, yet effective, diagnostic work, you can uncover the root cause of your p0442 code. From this point, a quick fix should have you back on the road, in the vast majority of cases.

What Does The p0442 Code Mean?

Trouble code p0442 is designated as “evaporative emission control system leak detected small leak.” 

This code is set by the PCM when a very small fuel vapor leak has been detected within the evaporative emissions system.

The evaporative emissions system circulates fuel vapor through EVAP hoses in a way that prevents it from being released into the atmosphere.

These fuel vapors are stored within a vehicle’s charcoal canister until they can be recycled back into the engine’s intake manifold.

A vehicle’s evaporative emission system undergoes a leak test upon startup. If a malfunction is detected in the form of an EVAP leak, an error code, or DTC is stored.

What Caused The p0442 code (Possible Symptoms)?

Several minor evap system issues can lead to the presence of a small leak. In most cases, these issues are easily addressed and remedies.

Some of the most common causes of an EVAP system leak include:

  • Faulty, damaged, incorrect, or loose gas cap
  • Compromised vent o-ring seal
  • Defective EVAP purge valve
  • Failed leak detection pump
  • Problematic vent valve

One of the unique characteristics of evap code p0442 is that no additional symptoms generally present themselves.

With the exception of an illuminated check engine light, few are aware that their vehicle is experiencing an EVAP related issue until this fact is confirmed through the use of an OBD2 compatible scan tool.

Check this article for more on the p0442 code.

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Did you know: The P0442 error code is one of the most common engine codes that pops up for the evaporative emissions control system, a.k.a the EVAP system. Lucky for you, sometimes this is a super simple fix!

How To Diagnose An p0442 Code?

Diagnosing an evaporative emissions-related fault such as p0442 can often be a process of trial and error.

However, a basic diagnostic course of action can speed assist in achieving a quick and accurate diagnosis.

  1. Retighten Fuel Cap
  2. Replace Fuel Cap
  3. Perform a Visual Inspection
  4. Conduct Further Scan Tool Diagnostics

Step 1: Retighten Fuel Cap 

The simplest way to begin when diagnosing a p0442 fault code is to remove, reinstall, and retighten your gas cap.

You will then clear this trouble code, and test drive the vehicle in question to see if the check engine light returns.

Step 2: Replace Fuel Cap

If your vehicle’s check engine light returns, the next course of action is to replace the vehicle’s gas cap, and again clear the diagnostic trouble code.

In up to 90 percent of cases, steps 1 and 2 will solve the issue at hand.

Step 3: Perform a Visual Inspection

If the problem persists, a thorough inspection of all EVAP components, including hoses, will be required. 

This can also be aided with the use of a smoke machine, which will make any leaks visually obvious.

Step 4: Conduct Further Scan Tool Diagnostics- 

If you are still plagued by a recurring p0442 diagnostic trouble code, further diagnostics will be required.

This process is facilitated by the use of a professional-grade scan tool. Many tests of this nature will be make and model specific.

However, the vast majority of these tests will center around operational testing of a vehicle’s EVAP purge solenoid, as well as computer controlled leak checks.

Read More >> What Does The P0420 Engine Code Mean?

P0442 Repair Simplified

Although it is quite easy to become dismayed at the sight of a check engine light, the issue at hand is often far less dire than what might one think.

More often than not, this is the exact case when dealing with a p0442 fault code.

By taking the time to carefully diagnose your vehicle’s diagnostic trouble code, and making any necessary repairs, your vehicle will be back at the top of its game in no time.

About Your Mechanic

About Josh Boyd

I’ve been an ASE Certified automotive/heavy equipment technician since 2010. I began my career performing basic automotive maintenance at a service center before working as a Toyota technician at my local dealership.

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