CodelampCame back after a repair
P0442 came back after a new gas cap
P0442
- In plain words
- The fuel vapor system has a small leak.
- Standard name
- Evaporative Emission System Leak Detected (Small Leak)
- System
- Fuel vapor (EVAP) system
General information, not a mechanic's diagnosis: have a mechanic confirm before any repair.
What the computer saw
A new cap fixes P0442 only when the old cap's seal was the leak. If the code returns after the computer has rerun its test, the small leak is elsewhere in the system.
Likely causes, most common first
- A small crack in an EVAP hose. Rubber hardens and cracks with age.
- A vent or purge valve that does not seal. A slight leak when closed.
- A rusted filler neck. The cap seals against the neck; a pitted neck leaks even with a new cap.
- A cracked charcoal canister. Less common.
What you can note yourself
- Note whether the light went off at all after the new cap, and for how long.
- Allow several days of driving after any fix before judging it.
What to tell the shop
- When the cap was replaced and how long the light stayed off.
- Ask for a smoke test to find the leak.
This page gives no verdict on whether a car is safe to drive; a mechanic can.