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.

Real-world scan data

Seen in

850

scans in the past year

Found in

0.1%

of scans

0.2%

of scans that found faults

Appears alongside · share of P0442 scans

P0455in 20.8% of scans

P0300in 12.7% of scans

P0420in 8.8% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.