Detect and Prevent Common Emissions Faults

Cost Savings

Checklist Tasks

• Scan OBD-II for emissions codes to find faults early.
• Inspect EVAP hoses for cracks to prevent vapor leaks and warning lights.
• Test oxygen sensors for slow response indicating sensor wear.
• Check purge valve for sticking or failure to prevent high emissions.
• Examine catalytic converter for rattles or discoloration warning of damage.
• Check gas cap seal to prevent leaks causing failed emissions tests.
• Clean or replace EGR valve if blocked by carbon to reduce NOx emissions.
• Monitor fuel trim values to detect air or fuel delivery issues.
• Test for exhaust leaks before the oxygen sensors to avoid false readings.
• Check for software updates or relevant emissions-related recalls.
• Verify all readiness monitors are set before inspection.