Trouble codes › P0442
P0442 Evaporative Emission System Leak Detected (Small Leak)
EVAP
P0442 means the EVAP system has a small leak, often a worn gas cap seal or a cracked hose.
The EVAP system stores fuel vapor from the tank and burns it in the engine instead of letting it into the air. The engine computer seals the system now and then and checks that it holds vacuum or pressure. P0442 means it found a small leak, about the size of a 0.040-inch hole.
Safe to drive. It doesn't affect how the engine runs, but it will fail an emissions inspection and lets fuel vapor escape.
Common causes
- A loose, worn or wrong gas cap, or a worn cap seal
- A cracked EVAP hose or loose connection
- A leaking purge valve or vent valve
- A cracked charcoal canister or a leaking filler neck
Symptoms
- Check-engine light
- Sometimes a faint fuel smell near the car
- Usually nothing else
Common on: Chevrolet Silverado 1500
What to check first
- Tighten the gas cap until it clicks, and look at its rubber seal for cracks. Replace it if it's worn (use one made for your vehicle).
- Clear the code and drive normally for a few days: the EVAP test only runs under certain conditions (often a cold start with the fuel tank between about 1/4 and 3/4 full).
- If it comes back, have the EVAP system smoke-tested: it's the quickest way to find small leaks.
- Check the hoses around the charcoal canister, usually near the fuel tank.
What does P0442 mean on your vehicle?
The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.
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Related codes
General guidance for P0442 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.