Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
EVAP System, Checking for Leaks
Special tools, testers and auxiliary items required
- Smoke tester.
- EVAP and Fuel Supply System Vacuum hose and line routing diagram.
- Secure all hose connections using hose clamps appropriate for the model type
- Replace seals and gaskets when performing repair work.
Leak checking
- Using a Smoke tester, check the Evaporative Emission (EVAP) canister system for leaks.
- Always follow the manufacturers directions for the proper installation and operation of the Smoke tester being used.
If a leak is detected:
- Check the fuel filler cap seal for damage and for proper installation. Replace if necessary.
- Check the seals under the locking flanges and the union nuts are properly tightened on the fuel tank.
- Check all hose connections of the fuel supply system and replace or repair any leaking lines.
- Check all hose connections of the EVAP system and replace or repair any leaking lines.
- Repair or replace any damaged component.
If no leaks are found in the EVAP and Fuel Supply System:
- Erase the DTC memory if a DTC was set. Refer to → Diagnostic Mode 04 - Reset/Delete Diagnostic Data .
- Perform a road test to verify repair.
If a DTC was set and does not return:
Repair complete, Generate readiness code. Refer to → Readiness Code Description .
- End diagnosis.
If the DTC does return and no leaks are found in the EVAP and Fuel Supply System:
- Check the DTC memory for any DTC codes pertaining to the EVAP and Fuel Supply Systems. If a DTC is stored, perform the diagnostic test procedure for the suspected component. Refer to → Diagnostic Mode 03 - Interrogating Fault Memory .
End diagnosis.
If the DTC does return and no leaks are found in the EVAP and Fuel Supply System:
- Check the DTC memory for any DTC codes pertaining to the EVAP and Fuel Supply Systems. If a DTC is stored, perform the diagnostic test procedure for the suspected component. Refer to → Diagnostic Mode 03 - Interrogating Fault Memory .
End diagnosis.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.