P0442: EVAP Small Leak — Causes and Diagnosis
Key Takeaway
P0442 means a small leak in the EVAP system. Here are the most common causes.
What Is P0442?
P0442 indicates the ECM detected a small leak in the EVAP (Evaporative Emission Control) system — the sealed system that captures fuel vapors.
Common Causes (in order of likelihood)
| # | Cause | Fix Cost |
|---|---|---|
| 1 | Loose or worn gas cap | $0 – $15 |
| 2 | Cracked EVAP hose | $50 – $150 |
| 3 | Faulty purge valve | $100 – $200 |
| 4 | Faulty vent valve | $100 – $200 |
| 5 | Damaged charcoal canister | $150 – $400 |
| 6 | Cracked filler neck | $150 – $300 |
Diagnosis Steps
1. Check the gas cap first — tighten and clear code.
2. If code returns, perform a smoke test to find the leak visually.
3. Inspect EVAP hoses for cracks.
4. Test purge and vent valves.
ProHow Steer Helps
Steer identifies P0442, rates it as low severity, and guides you through the diagnosis starting with the cheapest fix.
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