Your OBD-II diagnostic scanner may register a P0442 EVAP leak detected diagnostic trouble code. If so, you are probably wondering, how do I fix trouble code P0442?
Your vehicle’s powertrain control module monitors the Evaporative Emission Control System for leaks and other problems.
If you see a P0442 DTC, you know there is a fuel vapor leak somewhere in the EVAP system. The small leak code tells you that the leak is probably minor.
What Does the P0442 Code Mean?
The Code P0442 stands for “Evaporative Emission Control System Leak Detected (Small Leak)”.
The P0442 code is a diagnostic trouble code (DTC) that indicates a small leak in a vehicle’s evaporative emission control (EVAP) system. The EVAP system prevents fuel vapors from escaping into the atmosphere, which helps reduce air pollution.
The Evaporative Emission System is designed to prevent gasoline vapors from escaping into the atmosphere, and is built around a series of valves, rubber hoses, and a charcoal canister meant to collect vapors as they build up.
These vapors are then systematically sent to the engine to be burned off. The computer regularly checks for leaks within this system, either by pumping in air, or by pulling a vacuum, and measuring the time it takes to reach a certain level.
When a leak is detected the computer will command the check engine light on and set a P0440, which designates a problem in the system, and another code, such as P0442, to describe the size of leak or other problems in the system.
What are the Possible Causes of the P0442 Code?
The most common causes of the P0442 code are the following:
- A loose or incorrectly affixed gas cap.
- A gas cap that does not meet vehicle manufacturer standards.
- A tiny crack or hole in a fuel vapor hose or tube.
- A different type of leak somewhere else in the EVAP system.
- A faulty vent or purge valve.
- A bad vent seal.
- An unreliable leak detection pump .
Common symptoms of a P0442 error code
- Your vehicle’s check engine light is on
- You might smell fuel inside or near the vehicle
- You could notice a small decrease in fuel efficiency
- If your state requires emissions testing, this code would cause your vehicle to fail
How a Professional Mechanic Inspects and Diagnoses the P0442 Code
When a professional mechanic is tasked with inspecting and diagnosing the P0442 code, they will typically follow a systematic process to pinpoint the root cause of the issue. Here’s a breakdown of how a mechanic may approach the diagnosis:
Scan the Vehicle’s Computer for Trouble Codes
The first step in diagnosing the P0442 code is to connect a scan tool to the vehicle’s onboard computer system and retrieve any stored trouble codes. This will provide the mechanic with a starting point for their diagnosis.
Inspect the Gas Cap
The mechanic will inspect the gas cap to ensure that it’s properly tightened and in good condition. If the cap is loose or damaged, it must be replaced.
Check the EVAP System Hoses
The mechanic will inspect the EVAP system hoses for signs of damage or wear. They may use a smoke machine to detect any leaks in the system.
Test the EVAP System Purge Valve
The mechanic will test the EVAP system purge valve to ensure it functions properly. They may use a multimeter to test the valve’s electrical connection and check for any signs of physical damage.
Inspect the Charcoal Canister
The mechanic will inspect the charcoal canister for signs of damage or wear. They may also check the canister’s filter to ensure that it’s not clogged.
Check the Fuel Tank for Leaks
The mechanic will inspect the fuel tank for signs of damage, such as rust or corrosion, that may be causing a leak in the system.
Repair or Replace Faulty Components
Once the root cause of the P0442 code has been identified, the mechanic will repair or replace any faulty components. This may include replacing a damaged gas cap, repairing or replacing EVAP system hoses, replacing a faulty purge valve, or replacing a damaged charcoal canister.
Clear the Trouble Codes and Retest
After the repairs have been made, the mechanic will clear the trouble codes from the vehicle’s computer system and retest the system to ensure that the P0442 code has been resolved.
Overall, diagnosing and repairing the P0442 code can be a complex process that requires a thorough understanding of your vehicle’s evaporative emissions control system.
Suppose you’re not comfortable diagnosing and repairing the issue on your own. In that case, it’s always best to consult a professional mechanic to ensure your vehicle runs as efficiently and safely as possible.
What is the cost to resolve a P0442 code?
Estimated diagnostic cost: $100–$200
Estimated part(s) + labor cost: $50
The diagnosis might be the most expensive part of the bill. Unlike larger leaks, where components have failed or hoses have broken in half, small leaks are much harder to find.
An initial diagnostic fee of $100 is customary, with many shops charging an additional $100 if the leak is not found within an hour, or if the components are difficult to access.
Many times the repair is a new piece of hose, a rubber gasket between two components, or a new fuel cap, all of which will keep the repair portion of the bill under $50.
However, there are cases where small leaks develop in the filler neck or even the gas tanks (the metal ones), which will bring repair costs up to the $500–$600 dollar range.
Keep in mind, pricing will vary by location and your vehicle make and model. Save time and money by using Openbay to compare pricing and book an appointment with a service center in your area.