Visual and diagnostic inspection of the emissions control system components to verify compliance with federal and state emissions standards.

Warnings

Tools required

Preparation

1. Ensure vehicle has been driven at least 50 miles since last code clear to allow emissions monitors to complete readiness cycles
2. Park vehicle on level surface and apply parking brake
3. Turn ignition off and allow engine to reach inspection temperature per local requirements
4. Locate OBD-II diagnostic port under driver side dashboard near steering column

Procedure

1. 1

   Perform OBD-II System Check
   Connect OBD-II scan tool to diagnostic port. Turn ignition to ON position without starting engine. Verify communication with vehicle ECU and check for malfunction indicator lamp (MIL) illumination on instrument cluster. Record any diagnostic trouble codes (DTCs) present in all modules, particularly powertrain and emissions-related codes.
2. 2

   Check Emissions Monitor Readiness Status
   Using scan tool, navigate to monitor readiness screen (Mode $01 PID $01). Verify that all required emissions monitors have completed their drive cycles and show 'Ready' status. For 2016-2024 Tucson 2.5L, required monitors typically include: Catalyst, Evaporative System, Secondary Air System (if equipped), Oxygen Sensor, and Heated Catalyst. Document any incomplete monitors.
3. 3

   Inspect Gas Cap and Evaporative System
   Remove fuel filler cap and inspect gasket for cracks, deterioration, or damage. Check cap for proper sealing surface condition. Verify tether is intact. Visually inspect evaporative emission control system canister location near rear fuel tank area for physical damage, loose connections, or signs of charcoal leakage. Check vapor lines for cracks or disconnection.
4. 4

   Inspect Catalytic Converters
   From underneath vehicle, visually inspect catalytic converters (front and rear on AWD models) for physical damage, cracks, or signs of overheating indicated by discoloration. Check heat shields for secure mounting and absence of rattles. Verify all converter mounting hardware is tight and no exhaust leaks are present at flanges or connections.
   ⚠Catalytic converters and exhaust system can remain extremely hot for extended periods after engine operation
5. 5

   Inspect Oxygen Sensors
   Locate and visually inspect all oxygen sensors (typically 2 upstream and 2 downstream sensors on AWD 2.5L). Check sensor wiring harnesses for damage, melting, or exposure to excessive heat. Verify connectors are fully seated and locking tabs engaged. Look for signs of contamination on sensor bodies such as coolant, oil, or silicone deposits.
6. 6

   Check PCV System and Intake Components
   Open hood and inspect positive crankcase ventilation (PCV) valve and hoses for proper connection. Check for collapsed, cracked, or oil-saturated hoses. Inspect air intake system from air filter housing to throttle body for loose clamps, cracks in ducting, or any unmetered air leaks. Verify air filter is present and not excessively contaminated.
7. 7

   Inspect Exhaust Gas Recirculation System
   Locate EGR valve on intake manifold. Visually inspect EGR valve, cooler, and associated vacuum or electrical connections for damage or disconnection. Check for carbon buildup visible at valve opening. Verify wiring harness connector is secure if electrically controlled. Look for signs of exhaust leaks at EGR cooler connections.
8. 8

   Check for Exhaust Leaks
   Perform complete visual inspection of entire exhaust system from exhaust manifold to tailpipe. Look for signs of soot deposits indicating leaks, corroded or separated joints, damaged gaskets, or loose clamps. Pay particular attention to manifold-to-pipe connection and all flange joints. For AWD models, inspect both exhaust banks and Y-pipe connection.
9. 9

   Verify Fuel System Integrity
   Inspect visible fuel lines in engine bay and under vehicle for leaks, cracks, or damage. Check fuel rail and injector connections for signs of seepage. Verify fuel tank has no visible damage or corrosion. Check that all fuel system protective shields are in place and secured.
   ⚠️Any fuel leaks present an immediate fire hazard and must be repaired before continuing operation
10. 10

    Document Inspection Results
    Record all findings including DTC codes, monitor status, visual inspection results, and any deficiencies found. Note MIL status (on/off). For failed inspections, document specific failure reasons. Clear codes only after all required documentation is complete and if permitted by inspection protocol. Turn ignition off and disconnect scan tool.

Reassembly

1. Reinstall fuel filler cap by turning clockwise until multiple clicks are heard
2. Ensure all inspection covers, shields, and components disturbed during inspection are properly reinstalled
3. Close hood and verify secure latching

Verification

• If MIL was off and no codes present, verify inspection pass criteria met per local jurisdiction requirements
• Confirm all emissions monitors show 'Ready' status or meet allowable incomplete monitor limits for your area
• Start engine and verify MIL illuminates during bulb check and extinguishes after engine start
• Verify no new DTCs set during inspection process
• Provide customer with documentation of inspection results and any recommended repairs if applicable

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