Visual and diagnostic inspection of emissions control systems including catalytic converters, oxygen sensors, EVAP system, and PCV components to verify proper operation and compliance.

Warnings

Tools required

Preparation

1. Ensure vehicle has been driven for at least 10-15 minutes to reach operating temperature, then allowed to cool completely
2. Park vehicle on level ground and engage parking brake
3. Ensure adequate lighting around and under vehicle for visual inspection
4. Have vehicle registration and previous inspection records available for reference

Procedure

1. 1

   Check for diagnostic trouble codes
   Connect OBD-II scan tool to diagnostic port located under driver side dash. Turn ignition to ON position without starting engine. Retrieve and record any diagnostic trouble codes (DTCs). Check for pending codes and freeze frame data. Note the malfunction indicator lamp (MIL/Check Engine Light) status.
2. 2

   Verify readiness monitors
   Using scan tool, check emission monitor readiness status. For 2015-2020 F-150 3.5L EcoBoost, verify that all required monitors (Catalyst, EVAP, O2 Sensor, O2 Heater, EGR if equipped) show 'Ready' status. Most jurisdictions allow one non-ready monitor except Catalyst and Misfire which must always be ready.
3. 3

   Inspect fuel cap and EVAP system
   Remove fuel cap and inspect gasket for cracks, damage, or debris. Verify cap clicks 3-4 times when tightening. Visually inspect EVAP canister located near fuel tank on driver side frame rail for physical damage or loose connections. Check all visible vapor lines for cracks, disconnections, or damage.
4. 4

   Inspect catalytic converters
   Raise vehicle safely or use inspection mirror to examine both catalytic converters from underneath. The 3.5L EcoBoost has close-coupled cats near the turbochargers. Check for physical damage, cracks, or discoloration indicating overheating. Listen for rattling when tapping gently with plastic tool, which indicates internal substrate failure.
   ⚠Catalytic converters retain heat for extended periods - verify components are cool before touching
5. 5

   Inspect oxygen sensors
   Locate and visually inspect all four oxygen sensors (two upstream pre-cat sensors near turbochargers, two downstream post-cat sensors). Check sensor wiring harnesses for damage, melting, or oil contamination. Verify connectors are fully seated and locking tabs intact. Check for exhaust leaks near sensor mounting locations.
6. 6

   Check PCV system
   Open hood and locate PCV valve on driver side valve cover. Remove and shake PCV valve - it should rattle freely indicating the internal check valve moves. Inspect PCV hoses and connections for cracks, hardening, or disconnections. Check oil separator located in valley between cylinder banks for secure mounting and connection integrity.
7. 7

   Inspect air intake system
   Remove engine cover by pulling upward on front and rear attachment points. Visually inspect air filter housing, intake tubes, and connections from air box to turbocharger inlets. Check for loose clamps, cracks in ducting, or unmetered air leaks. Verify air filter condition - replace if excessively dirty as this affects emissions.
8. 8

   Check exhaust system integrity
   Inspect entire exhaust system from manifolds to tailpipe for leaks, damage, or missing components. Pay special attention to turbocharger outlet connections, flex joints, and exhaust hangers. Any exhaust leaks upstream of oxygen sensors will affect emissions readings and cause failed inspection.
9. 9

   Verify EGR system operation (if equipped)
   On vehicles with EGR, use scan tool to command EGR valve open while monitoring position sensor data. Verify valve responds to commands. Visually inspect EGR valve and cooler for carbon buildup at connections. Check EGR cooler for coolant leaks which indicate internal failure affecting emissions.
10. 10

    Document findings and clear codes if necessary
    Record all inspection results including DTC status, monitor readiness, and visual inspection findings. If no hard faults found and only soft codes present, clear codes and advise drive cycle completion. If hard faults present, document for repair before re-inspection. Print or record scan tool data for documentation.

Reassembly

1. Reinstall engine cover ensuring all mounting points are fully seated
2. Verify fuel cap is properly tightened with 3-4 clicks
3. Ensure all connectors and components disturbed during inspection are properly reconnected
4. Remove scan tool and verify all access panels and covers are secured

Verification

• Verify no diagnostic trouble codes present and MIL is not illuminated
• Confirm all required emission monitors show 'Ready' status for jurisdiction requirements
• Start engine and verify smooth idle with no unusual noises from exhaust or intake systems
• Check for any new fluid leaks introduced during inspection
• Provide customer with inspection report detailing monitor status and any advisories

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