Visual and functional inspection of emissions-related components to verify proper operation and identify potential issues affecting emissions compliance.

Warnings

Tools required

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely before inspection
3. Ensure vehicle has been driven at least 50 miles since last battery disconnect to complete readiness monitors
4. Have VIN and registration available for documentation

Procedure

1. 1

   Scan for diagnostic trouble codes
   Connect OBD-II scanner to diagnostic port located below driver side dashboard. Turn ignition to ON position without starting engine. Retrieve and document all stored and pending diagnostic trouble codes (DTCs). Check readiness monitor status - all monitors except EVAP and O2 sensor heater should be complete for vehicles with less than 200 miles since battery disconnect.
2. 2

   Inspect fuel cap and EVAP system
   Remove fuel cap and inspect gasket for cracks, deterioration, or damage. Check cap for proper sealing surface condition. Verify cap clicks 3-5 times when tightened. Visually inspect EVAP canister located under vehicle near fuel tank for physical damage or charcoal debris. Check all visible EVAP hoses for cracks, disconnection, or deterioration.
3. 3

   Inspect air intake system
   Open hood and visually inspect air intake system from air filter box to throttle body. Check air filter element for excessive dirt or damage. Verify all air box clips are secure. Inspect intake ducting for cracks, holes, or loose connections. Check for any unmetered air leaks that could affect air-fuel ratio.
4. 4

   Inspect exhaust system
   Visually inspect entire exhaust system from engine manifold to tailpipe. Check for leaks, cracks, rust perforation, or physical damage. Pay special attention to flex pipe, catalytic converter, and all connection joints. Look for soot stains indicating leak points. Verify all exhaust hangers are intact and exhaust is properly supported.
5. 5

   Inspect oxygen sensors and wiring
   Locate oxygen sensors in exhaust system (typically two sensors: upstream before catalytic converter and downstream after converter). Inspect sensor wiring harnesses for heat damage, chafing, or cuts. Verify connectors are fully seated and locked. Check that sensor wiring is properly routed away from hot exhaust components.
6. 6

   Inspect PCV system
   Inspect PCV valve and hoses accessible from engine bay. Check PCV hose connections at valve cover and intake manifold for security and condition. Verify no oil residue indicating leaks. Listen for PCV valve rattle when shaken (indicates valve is not stuck). Inspect breather hoses for cracks or deterioration.
7. 7

   Check for vacuum leaks
   Visually inspect all vacuum hoses visible in engine bay for cracks, hardening, or disconnection. Check brake booster vacuum hose, EVAP purge valve lines, and any emission control vacuum lines. Verify all hose connections are secure. Look for signs of deterioration at hose ends where they connect to components.
8. 8

   Inspect engine for oil leaks
   Visually inspect engine for oil leaks that could contaminate oxygen sensors or catalytic converter. Check valve cover gasket, oil pan gasket, and oil filter area. Significant oil leaks can affect emissions system performance and should be documented.
9. 9

   Verify MIL operation
   Turn ignition to ON position without starting engine. Verify Malfunction Indicator Lamp (check engine light) illuminates on instrument cluster. Start engine and verify MIL extinguishes if no fault codes are present. If MIL remains illuminated or does not illuminate during bulb check, document for repair.
10. 10

    Document inspection results
    Record all findings including any DTCs, visual defects, leaks, or component damage. Note readiness monitor status. Clear any informational codes only if customer authorizes and understands monitors will need to reset. If DTCs are present, provide customer with explanation and repair recommendations.

Reassembly

1. Ensure all air intake components are properly secured and air box clips are fastened
2. Verify fuel cap is properly tightened with 3-5 clicks
3. Disconnect OBD-II scanner and ensure diagnostic port cover is reinstalled if equipped

Verification

• Confirm no DTCs are present or all existing codes have been documented
• Verify MIL (check engine light) operates correctly during key-on bulb check
• Confirm all readiness monitors show completion status appropriate for vehicle mileage since last reset
• Ensure no visible leaks, damage, or disconnected components in emissions system
• Provide customer with written inspection report including any recommended repairs

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