P0442: How to Diagnose & Fix — Evaporative Emission Control System Leak Detected (Small Leak)
42 vehicles · 18 makes · $20-$2,500 repair
How to diagnose and fix P0442: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chrysler 300 · 2011–2023
Evaporative emission control system develops small leaks triggering P0456 code. Most commonly failed gas cap, chaffed EVAP purge pipe harness, or failed purge solenoid. Triggers check engine light and prevents emissions testing pass.
Common Symptoms
- Check engine light with P0456 code
- "Gas cap" warning even with cap tight
- Fuel smell near vehicle
- Failed emissions test
- No performance or drivability issues
How to Fix
Start with gas cap replacement ($20-40). If code returns, smoke test EVAP system to locate leak. Common fixes: replace purge solenoid, repair chaffed wiring harness, or replace cracked EVAP hoses.
Sources for this issue (1)
Toyota FJ Cruiser · 2007–2014
The FJ Cruiser's A/C system is prone to compressor clutch failure and evaporator core leaks. The evaporator is located behind the dashboard, making replacement extremely labor-intensive. The A/C system struggles in hot climates, especially when off-roading at low speeds.
Common Symptoms
- A/C blows warm air
- A/C compressor clicking on and off rapidly
- Weak airflow from vents
- Musty smell from vents (evaporator leak)
- Refrigerant needs recharging frequently
How to Fix
For compressor clutch: replace A/C compressor assembly (Denso 471-1026 or Toyota 88310-35C60). For evaporator: replace evaporator core (Toyota 88501-35120) - this is a full dash removal job, 8-12 hours labor. Replace receiver/drier, expansion valve, and O-rings whenever the system is opened. Evacuate and recharge with R-134a.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 88320-35700 genuine cooler compressor assembly
early compressor branch after pressure, electrical and mechanical diagnosis confirms compressor failure Fitment/availability: Cataloged for 2007-2010 Toyota FJ Cruiser 4.0L; production overlap requires VIN confirmation Fitment/availabili…
- Toyota 88320-6A540 genuine compressor assembly
late compressor branch after pressure, electrical and mechanical diagnosis confirms compressor failure Fitment/availability: Cataloged for 2010-2014 Toyota FJ Cruiser 4.0L; production overlap requires VIN confirmation Fitment/availabilit…
- Toyota 88501-35151 genuine A/C evaporator core
evaporator replacement only after an electronic/dye leak test localizes refrigerant loss to the evaporator Fitment/availability: 2007-2014 Toyota FJ Cruiser; replaces 88501-35150, 88501-60300 and 88501-60430; confirm VIN/current superses…
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Toyota Tacoma · 2016–2023
The A/C system can develop a musty or moldy smell when first turned on. This is caused by moisture accumulation and mold/bacteria growth on the evaporator. Common in humid climates and vehicles that use A/C infrequently.
Common Symptoms
- Musty smell when A/C starts
- Mold or mildew odor
- Smell goes away after a few minutes
- Worse in humid weather
- Allergic reactions possible
How to Fix
Use A/C evaporator cleaner spray through the cabin air filter opening or vents. Replace cabin air filter regularly. Run A/C on fresh air mode for a few minutes before turning off to dry evaporator. Professional evaporator cleaning available.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 00289-ACRKT genuine A/C Refresher Kit
clean and deodorize a contaminated evaporator case Fitment/availability: Toyota evaporator deodorizing/cleaning service kit; use only after confirming the odor is microbial evaporator contamination and follow the kit procedure Fitment/av…
- Toyota 88508-04010 genuine deodorant cabin-air filter
replace a dirty or odor-contaminated cabin filter after the odor source is corrected Fitment/availability: 2016-2023 Toyota Tacoma cabin-filter application; confirm VIN and HVAC housing Fitment/availability: Add to Cart live when reviewed
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipReplace cabin air filter regularly.
- TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
Sources for this issue (1)
Mazda Mazda5 · 2006–2015
Dodge Journey · 2009–2020
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P0442 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0442 mean?
P0442 stands for "Evaporative Emission Control System Leak Detected (Small Leak)." This emissions code means the evaporative emission (EVAP) control system has detected a small leak. The EVAP system seals the fuel tank and captures gasoline vapors, routing them to be burned in the engine instead of escaping into the air, and the computer periodically pressure- or vacuum-tests the system to confirm it's sealed. A small leak the size of about a 0.040-inch hole will set this code. By far the most common and cheapest cause is a loose, damaged, or missing gas cap, so that's the first thing to check, though any cracked hose or worn seal in the system can also trigger it.
What are the most common causes of P0442?
The most common causes of P0442 are: Loose, damaged, or missing fuel filler cap, Worn or cracked gas cap seal, Cracked or disconnected EVAP hose or line, Faulty purge valve or vent valve, Damaged O-ring or seal at the fuel tank or filler neck, Small crack in the charcoal canister, Leaking fuel tank sending unit gasket. The specific cause varies by vehicle.
How much does it cost to fix P0442?
Repair costs for P0442 range from $20 to $2,500, depending on the vehicle and root cause.
Which vehicles are affected by P0442?
Au7o has documented P0442 across 42 vehicle models from 18 manufacturers: Chevrolet, Chrysler, Dodge, Ford, GMC, Honda, Hyundai, Infiniti, Jeep, Kia, Mazda, Nissan, Pontiac, RAM, Saturn, Subaru, Toyota, Volkswagen.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.