P0442: Evaporative Emission Control System Leak Detected (Small Leak)
A small leak has been detected in your EVAP system. Unlike P0455 (large leak), this is a pinhole or very small leak. Often caused by a worn gas cap seal, tiny crack in an EVAP hose, or failing EVAP canister vent valve.
Symptoms
- Check engine light only
- Occasional faint fuel smell
- Fails emissions test
Causes (Ranked by Likelihood)
50 Most Common OBD2 Codes - Free Printable
Plain-English explanations for the codes mechanics charge $100+ to diagnose.
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DIY Fix Steps
⚠ Safety first: work on a cold engine, chock wheels, use jack stands - never rely on a floor jack alone.
Start with a new OEM-spec gas cap. The small leak threshold is sensitive enough that a worn cap seal will trigger P0442. Clear code, drive 3 warm-up cycles.
Trace all rubber EVAP lines. Small leaks are hard to see - bend each hose to check for cracking. Pay attention to lines near heat sources.
P0442 small leaks are nearly impossible to find without a smoke machine. Most shops charge $50-80 to smoke test the system and pinpoint the leak.