P0442
EVAP System Leak Detected (small leak)
Evaporative emissions (EVAP)
Generic OBD-II
Low
What it means
P0442 means the evaporative emission (EVAP) system has a small leak, so fuel vapor is escaping instead of being captured and burned. It doesn't affect how the engine runs or starts — it's purely an emissions fault. A loose or worn fuel cap is the most common cause, so start there before chasing hoses or valves.
Low
Can I keep driving? Yes — a small EVAP leak doesn't affect how the car runs or starts; it's an emissions issue, so fix it at your convenience to pass inspection and stop fuel-vapor loss.
Common symptoms
What you'll notice
- Check-engine light on (often the only sign)
- Faint fuel smell near the vehicle
- Fails an emissions or smog test
- No change in how the engine runs or starts
Common causes
Most likely first
- Loose, worn, or missing fuel cap — the most common causeLikely
- Cracked or disconnected EVAP hosesCommon
- Leaking or stuck purge valve or vent valveCommon
- Faulty EVAP charcoal canisterLess often
- Small leak in the fuel tank or filler neckLess often
How to diagnose & fix
Work through it in order
- Check the fuel cap: re-seat it until it clicks, inspect the seal, and replace it if worn. Clear the code and drive a few cycles.
- Inspect accessible EVAP hoses and connections for cracks or looseness.
- If it returns, have a smoke test done to pinpoint the leak.
- Test the purge and vent valves; replace whichever is leaking or stuck.
- Inspect the canister, fuel tank, and filler neck for damage.
FAQ
Quick answers
Is it safe to drive with P0442?+
Yes. A small EVAP leak has no effect on drivability or safety — it only means fuel vapor is escaping. Just don't expect to pass an emissions test until it's fixed.
Can I just clear P0442?+
You can, but if the leak is real it returns after a few drive cycles. Tighten or replace the fuel cap first, since that fixes many P0442 cases.
Related codes
Often seen with P0442
Read & clear P0442 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX