P0442 OBD-II Trouble Code: Evaporative Emission Control System Leak Detected (Small Leak)

Our certified mechanics come to you · Get a fair and transparent estimate upfront

EXCELLENT RATING ON

Cost of diagnosing the P0442 code

P0442 is a diagnostic trouble code (DTC) for "Evaporative Emission Control System Leak Detected (Small Leak)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $154.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $50.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate* Credit towards follow-up repair Earliest Availability
Ford $154.99 $50.0
Toyota $154.99 $50.0
BMW $164.99 $50.0

*Estimates may vary by market

SCHEDULE P0442 DIAGNOSTIC Get a fair and transparent estimate upfront

P0442 code definition

P0442 is a diagnostic trouble code (DTC) that is seen when a evaporative emission control system malfunction is present. This code may be seen with other EVAP system codes.

What the P0442 code means

P0442 is present in vehicles that have a small leak in the EVAP system. 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.

What causes the P0442 code?

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

What are the symptoms of 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 does a mechanic diagnose the P0442 code?

  • Hooks up a scan tool to the vehicle's DLC port and checks for any codes present

  • 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

  • Clears the codes and test drives the vehicle

  • Performs a visual inspection of the EVAP system, looking for any obviously cracked or broken components, and loose or damaged EVAP lines

  • Checks for cracks in the fuel tank or charcoal canister

  • Inspects the gas cap for proper fitment and condition, then tests with a gas cap tester

  • Uses a scan tool to monitor tank pressure and confirm if a leak is present

  • Tests the EVAP system solenoids and valves with scan tool

  • Performs a smoke test on the EVAP system, looking for smoke that indicates a vapor leak

Common mistakes when diagnosing the P0442 code

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.

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.

What repairs can fix the P0442 code?

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

Additional comments for consideration regarding the P0442 code

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.

Need help with a P0442 code?

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.

Check Engine Light
P0442
trouble codes

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0442 code.

SCHEDULE P0442 DIAGNOSTIC
Get a $50 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(8600)

Rating Summary
8017
273
65
46
199
8017
273
65
46
199
 at YourMechanic

Brandon

9 years of experience
133 reviews
Brandon
9 years of experience
Ford Escort L4-2.0L - Check Engine Light is on - Nashville, Tennessee
Brandon showed up ahead of schedule, was very personable and diagnosed my problems. He also scheduled my next appointments which will be with him.
 at YourMechanic

William

23 years of experience
33 reviews
William
23 years of experience
Lexus IS250 V6-2.5L - Check Engine Light is on - Mableton, Georgia
Arrived early which was great. William was courteous, and attentive to the issue. Even though it took several attempts I'm so happy he was determined to fix it and he did!
 at YourMechanic

Dan

40 years of experience
1080 reviews
Dan
40 years of experience
Plymouth Grand Voyager - Check Engine Light is on - Lawrenceville, Georgia
Mr. Dan Barber was quite patient, courteous and quite knowledgeable. From my observation, Mr. Barber appears to be quite professional.
 at YourMechanic

Christopher

9 years of experience
120 reviews
Christopher
9 years of experience
Ford Fiesta L4-1.6L - Check Engine Light is on - Smyrna, Georgia
Chris communicated with us each step of the way up until his arrival. He listened well, was knowledgeable, and was prepared. He took the time to diagnose the problem, explained the what, why and how and provided a solution. I would definitely recommend him and will use him again.


Related questions

What's the best way to check for Evap small leak. I'm getting code P0442
P0442 (https://www.yourmechanic.com/article/p0442-obd-ii-trouble-code-evaporative-emission-control-system-leak-detected-small-leak-by-spencer-clayton) indicates that you have a small leak in the evaporative emission system. Many times this is caused by a loose or faulty fuel cap (https://www.yourmechanic.com/services/gas-cap-replacement). Make sure that the cap is tight and in good condition, so that...
If my codes for my engine light is P0305, P0430, P0442.
To answer the question will I pass emissions if P0305 is fixed: if the two other codes are cleared after repairs are done for the P0305 code (https://www.yourmechanic.com/article/p0305-obd-ii-trouble-code-cylinder-5-misfire-detected-by-jay-safford) and they do not come back then you may pass emissions. The...

More related articles

P0376 OBD-II Trouble Code: Timing Reference High Resolution Signal B Too Many Pulses
P0376 code means there is an irregularity with the high resolution timing reference signal coming from the PCM requiring urgent attention.
P2788 OBD-II Trouble Code: Auto Shift Manual Adaptive Learning at Limit
P2788 means an issue with the adaptive learning system of the transmission which causes stalling at idle, harsh shifting and transmission overheating.
B1289 OBD-II Trouble Code: Servo Motor Potentiometer Air Intake Right Circuit Open
B1289 means there is an error with the servo motor potentiometer air intake right circuit, likely due to a defective servo motor or potentiometer.

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com