P0442 — EVAP System Leak Detected (Small Leak)
Can drive — fix at your convenience.
What P0442 means
P0442 indicates the EVAP system found a small vapor leak somewhere between the gas tank and the engine. Because the leak is small, the most frequent causes are a loose or aging gas cap, a tiny crack in a hose, or a slightly leaky valve. It doesn't affect performance, but it does mean a bit of fuel vapor is escaping.
Common symptoms
- Check engine light is on
- Possible faint fuel odor
- Failed emissions test
- No change in drivability or power
- Gas cap may feel loose or click oddly
Common causes
- Loose or improperly tightened gas cap
- Cracked gas cap seal or worn cap
- Small crack in an EVAP hose or line
- Slightly leaking purge or vent valve
- Cracked charcoal canister
Typical repair cost
$20 – $250
Varies by vehicle and root cause.
Frequently asked questions
Is it just the gas cap?
More often than not, yes. For a small-leak code like P0442, a loose or worn gas cap is the leading cause. Tighten it until it clicks, drive a few cycles, and if the light remains, a new cap ($20-60) is the cheapest thing to try first.
Can I drive with a P0442 code?
Yes. It's a small vapor leak that doesn't affect how the car runs or its safety. Just address it soon so the warning light clears and you can pass an emissions test.
How much will it cost to fix?
A gas cap is $20-60. If it turns out to be a hose or valve, expect roughly $100-250 with diagnosis and labor.
Is a small EVAP leak serious?
No, it's low severity. It won't harm your engine, but it lets a small amount of fuel vapor escape and will keep the check engine light on, so it's best to fix it.