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AutoCodes – Generic – P0442

P0442 Code - Evaporative Emission Control System Leak Detected Small Leak

Quick Answer

The engine off natural vacuum test is the small leak detection diagnostic for the evaporative emission system. Common causes include Missing or loose fuel cap, Incorrect fuel filler cap used, Fuel filler cap remains open or fails to close. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means
P0442 indicates Evaporative Emission Control System Leak Detected Small Leak.
Common causes
Common causes include Missing or loose fuel cap, Incorrect fuel filler cap used, Fuel filler cap remains open or fails to close.
Severity
Low - monitor the vehicle and repair when practical.
Can I drive?
The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.
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Code Popularity 88,752
How popular is this code, among other codes? Medium
What is this?
Table of contents Created and updated by William Orellana on Sep 30, 2023
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Code P0442 Description

The engine off natural vacuum test is the small leak detection diagnostic for the evaporative emission system. This diagnostic tests the Evaporative Emission (EVAP) system for a small leak when the key is turned OFF and the correct conditions are met. The heat from the exhaust system is transferred into the fuel tank while the vehicle is operating. Prior to running this test fuel volatility is analyzed and then factored into this test. When the vehicle is turned OFF and the EVAP system has sealed a change in the fuel tank vapor temperature occurs which results in a corresponding pressure change in the fuel tank vapor space. This change is monitored by the Engine Control Module (ECM) using the Fuel Tank Pressure (FTP) sensor input. With a leak in the system, the amount of pressure change will be less than that of a sealed system. The Diagnostic Trouble Code (DTC) will be set when the ECM detects a leak in the EVAP system that is greater than a calibrated amount.
OBDII Code P0442 - Evaporative Emission Control System Leak Detected Small Leak - AutoCodes.com
P0442 Code - Evaporative Emission Control System Leak Detected Small Leak
What does this mean?

What are the Possible Causes of the DTC P0442?

  • Missing or loose fuel cap
  • Incorrect fuel filler cap used
  • Fuel filler cap remains open or fails to close
  • Foreign matter caught in fuel filler cap
  • Leaking EVAP Canister
  • Leaking EVAP System Hose
  • Leaking Fuel Tank
  • Faulty Fuel Tank Pressure Sensor

How to Fix the DTC P0442?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The P0442 code means that the control module has detected a small leak in the Evaporative Emission (EVAP). A loose fuel tank filler cap is the most common cause that will trigger the P0442 code.









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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0442 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0442 code?

Need more information on how to fix the P0442 code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0442 Code

1. What are the common symptoms of OBDII code P0442?

The common symptoms of P0442 include the check engine light turning on, a slight decrease in fuel efficiency, and potential gas odors near the vehicle.

2. What are the possible causes of OBDII code P0442?

Possible causes of P0442 include a loose or damaged gas cap, a cracked or disconnected EVAP hose, a faulty purge valve, or a leak in the EVAP system.

3. How can I diagnose the source of the small leak triggering code P0442?

To diagnose the source of the small leak causing P0442, you can visually inspect the gas cap and EVAP system components, perform a smoke test to identify leaks, or use a scan tool to monitor EVAP system pressure.

4. Can a loose gas cap trigger code P0442?

Yes, a loose or improperly tightened gas cap is a common cause of P0442. Ensure the gas cap is securely tightened after refueling to see if the code clears on its own.

5. How can I repair OBDII code P0442 at home?

If the code is triggered by a loose gas cap, tightening it may resolve the issue. However, for other causes like a damaged hose or valve, it's recommended to seek professional help for proper diagnosis and repair.

6. Is it safe to drive with OBDII code P0442 active?

In most cases, it is safe to drive with code P0442 as it does not affect the immediate drivability of the vehicle. However, it's best to address the issue promptly to prevent potential long-term damage to the emissions system.

7. Will resetting the check engine light clear OBDII code P0442?

Resetting the check engine light may temporarily clear P0442, but if the underlying issue is not fixed, the code is likely to reappear after the vehicle completes its emissions self-check.

8. How much does it typically cost to repair OBDII code P0442 at a mechanic or dealership?

The cost to repair P0442 can vary depending on the cause of the issue and labor rates. On average, expect to pay between $100 to $300 for diagnosis and repair of this code.

9. Can extreme weather conditions affect the likelihood of triggering code P0442?

Extreme weather conditions, such as extreme heat or cold, can sometimes exacerbate issues in the EVAP system, potentially leading to the triggering of code P0442. Regular maintenance and inspections can help prevent such occurrences.

10. How frequently should I check the EVAP system to prevent OBDII code P0442?

It is recommended to include a visual inspection of the EVAP system components during routine maintenance checks, such as oil changes or tire rotations, to catch any potential issues early and prevent the triggering of code P0442.

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