P0442 means the engine control unit has detected a small leak in the evaporative emission control system. This system captures fuel vapours from the tank and routes them to the engine to be burned. A small leak allows vapours to escape, increasing hydrocarbon emissions.
P0442 means the engine control unit has detected a small leak in the evaporative emission control system. This system captures fuel vapours from the tank and routes them to the engine to be burned. A small leak allows vapours to escape, increasing hydrocarbon emissions.
P0442 is a evap system-related diagnostic trouble code classified as low severity. When your vehicle's ECU detects this condition, it stores P0442 and illuminates the check engine light.
If your vehicle has triggered P0442, you may notice one or more of these symptoms:
Here are the most common causes of P0442, ranked by how likely they are to be the culprit:
Generally yes, for short-term driving. A small EVAP leak does not affect engine performance or safety. You can drive normally, but repair before your next emissions inspection. A loose fuel cap is the most common cause.
Follow these steps to pinpoint the root cause of P0442:
Repair costs for P0442 vary depending on the root cause and your vehicle. Here are typical estimates:
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0442 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
These codes are often seen alongside P0442 or indicate related issues:
Yes. A loose, cracked, or missing fuel cap is the most common cause of P0442. The EVAP system is sealed, and even a slight gap at the cap allows vapours to escape. Always tighten the cap until you hear it click and replace it if the seal is worn.
Both indicate EVAP system leaks, but P0442 is a small leak (less than about 1mm equivalent orifice) while P0455 is a large leak. Small leaks are often from deteriorated hoses or a worn cap seal. Large leaks suggest a disconnected hose or missing cap.
If the cause was a loose fuel cap and you tighten it properly, the ECU will eventually clear the code after several successful EVAP system tests during normal driving. This may take 3-5 drive cycles. You can also clear it with a scanner.
It is not mechanically serious and will not damage your engine or affect performance. However, it means fuel vapours are escaping into the atmosphere, and the check engine light will cause a failed emissions inspection in any EU country.
Most modern vehicles use either a vacuum-based test or a dedicated leak detection pump. The system seals itself and applies a slight vacuum or pressure, then monitors whether it holds. A small drop indicates a leak, and the ECU sets P0442.
EVAP leak causing a check engine light? P0442, P0455, P0456 explained. Start with the gas cap. Causes, diagnosis, and repair costs in euros.
Learn how OBD2 works, find the port in your car, understand diagnostic trouble codes, know which problems you can fix yourself, and when to see a mechanic.
A check engine light with no symptoms can still mean a fault that costs you later. Read the code yourself for 15 euros to find out if runs fine is really fine.
Clearing a code before inspection resets the readiness monitors, and stations check those. Here are the OBD2 codes that fail, and why a fresh clear fails anyway.
Your car logged P0442. Skanyx reads it on any standard Bluetooth OBD2 adapter, tells you whether it is safe to keep driving, and shows the €10-€450 repair range so you know the number before a shop quotes you.
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