P0442 Code: Evaporative Emission Control System Leak Detected (Small Leak)
🟢 Low severity · drivable
Safe to drive — this is an emissions-system leak, not an engine problem. Fix it before your next emissions test.
What P0442 means
The evaporative emission (EVAP) system, which captures fuel vapors from the tank, has a small leak. It's an emissions issue and rarely affects how the vehicle runs.
Symptoms
- Check engine light is on
- Possible faint fuel smell
- Usually no driving symptoms
Common causes
- most common: Loose, missing, or damaged gas cap
- common: Small leak in an EVAP hose or fitting
- common: Faulty EVAP purge or vent valve
- less common: Small crack in the charcoal canister or fuel tank
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Tighten or replace the gas cap | Yes | $10–30 |
| Have a smoke test performed to find the exact leak | Mechanic | $50–150 |
| Replace a faulty purge or vent valve | Yes | $30–120 |
Frequently asked questions
Can I drive with a P0442 code?
Yes. It's an emissions leak and doesn't affect drivability. Just fix it before your next emissions inspection.
Is P0442 usually just the gas cap?
Often yes. A loose or bad gas cap is the most common cause, so tighten or replace it first before spending on diagnosis.
How much does it cost to fix a P0442?
As little as $10–$30 for a gas cap, or $50–$150 for a smoke test plus the cost of whatever part is leaking.
Related codes
P0455
P0455 Code: Evaporative Emission Control System Leak Detected (Large Leak)
P0456P0456 Code: Evaporative Emission System Leak Detected (Very Small Leak)
P0440P0440 Code: Evaporative Emission Control System Malfunction
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.