OBD-II · P0442
P0442 Code: Small EVAP Leak — Usually the Gas Cap
Evaporative emission system leak (small)
The short version
Yes, completely safe to drive immediately — this code only relates to fuel vapor emissions and doesn't affect performance or safety.
- Severity: Low
- Most common cause: Loose, missing, or damaged fuel cap
- 5 diagnosis steps in order
- 4 symptoms tied to this code
Darker bars are the more common causes; bar length is the top expected repair cost. Start with the dark, cheap causes before the expensive ones.
Can I keep driving?
Yes, completely safe to drive immediately — this code only relates to fuel vapor emissions and doesn't affect performance or safety.
Symptoms
- Usually no noticeable drivability symptoms
- Occasional faint fuel smell near the filler area
- Check engine light on with nothing else
- Failing an emissions inspection if applicable
Causes & repair cost
Loose, missing, or damaged fuel cap
Most common$5 – $25
Cracked EVAP hose
Possible$80 – $250
Faulty purge or vent solenoid valve
Possible$100 – $300
Cracked fuel tank itself (rare)
Rare$400 – $900
Most cases are solved with a cheap new gas cap; only if the code returns does cost rise for a proper smoke test and hose/valve diagnosis at a shop.
Estimate the repair for your carDiagnosis steps in order
- Check and tighten/replace the gas cap first
- Clear the code and drive for a few days to confirm
- Visually inspect EVAP hoses for cracks
- Use a smoke machine test to pinpoint the exact leak location
- Test purge/vent valves electrically
FAQ
Can I drive with a P0442 code?
Yes, completely safe — it doesn't affect vehicle performance.
Is the gas cap always the cause?
Not always, but it's by far the most common cause and worth checking first.
How do I know if the code will clear after a new cap?
Clear the code and drive several cycles; if it doesn't return, the issue is resolved.
What's the difference between P0442 and P0455?
P0442 is a small leak and P0455 is a large leak in the same EVAP system.
Related codes
All explained codes
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