Applicable Systems
OBD-II
Symptoms
EVAP system leak 0.040 inch or larger detected; fuel vapor escaping to atmosphere; emissions test failure.
Possible Causes
- Gas cap seal cracked
- EVAP hose crack/split
- Purge valve O-ring leak
- Charcoal canister crack
Troubleshooting Steps
- Step 1: Tighten gas cap and clear code
Code does not return after drive cycle - Step 2: Perform EVAP smoke test to locate leak
Leak found at specific component - Step 3: Inspect all EVAP hoses for cracks
All hoses intact - Step 4: Replace faulty gas cap or hose
No leaks after repair - Step 5: Clear code and perform EVAP self-test
EVAP self-test passes
How to Reset
Clear with OBD-II scanner; EVAP self-test requires cold soak (8+ hours) and warm-up.
Common Replacement Parts
- Gas Cap (OEM spec)
- EVAP Hose Kit
Frequently Asked Questions
- Q: How small is 0.040 inch leak?
Approximately 1mm diameter. This is the threshold for P0442. Smaller leaks may not trigger a code. Larger leaks trigger P0455 (large leak).
Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II