by Russell Krick Publisher The Goodheart-Willcox Co., Inc Tinley Park, Illinois © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only (16 Topics) Computer-controlled emission system service Emission maintenance reminder Inspecting emission control systems Exhaust gas analyzer Emissions testing programs Vacuum solenoid service © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only PCV system service Evaporative emissions control system service Thermostatic air cleaner system service EGR system service Air injection system service Pulse air system service © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Catalytic converter service Oxygen sensor service Emission control information sticker OBD II drive cycle © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Most emissions problems are caused by a malfunction in a system unrelated to the emission control system fuel system ignition system exhaust system computer control and electrical systems © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Scanning Emission Systems Connect the scan tool to the data link connector Check for diagnostic trouble codes (DTC’s) Retrieve data © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Scanning Emission Systems © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Scan Tool Readout A DTC B Description C Possible causes © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only The circuit turns on a dash light to indicate the need for emission control system service After repairs, the light must be turned off Refer to the service manual for numerous procedures © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Voltmeter Testing Probe between the signal wire and ground Fast-idle the engine to ensure the sensor is hot Record the minimum, maximum, and average voltages The voltage should go below 200 mV, above 800 mV, and average around 450 mV © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Voltmeter Testing © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Oscilloscope Testing Probe between the signal wire and ground © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Oscilloscope Testing The sensor output should vary as shown © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Oscilloscope Testing Zirconia sensor waveform © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Dual Trace Scope If the waveforms are too similar, it indicates a faulty converter © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Emission Systems Wiring © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only O2 Sensor Replacement Disconnect the negative battery cable Unplug the sensor connector Spray the threads with penetrating oil Use a special sensor socket Inspect for contamination © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only O2 Sensor © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only O2 Sensor Lazy sensor contaminated with carbon soot © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only The emission control information sticker contains important engine data evaporative emissions information schematics specifications © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Vehicle Emission Control Information © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only Performed: when the ECM has been disconnected from power when the diagnostic trouble codes have been erased to verify repairs, ensuring the DTC does not reoccur before an emissions test © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only OBD II Drive Cycle Each vehicle and manufacturer has its own drive cycle © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only OBD II Drive Cycle The vehicle is driven on a road test or dynamometer To begin, coolant has to be below a specified temperature The vehicle is driven through various conditions to allow computer to monitor all specified systems © Goodheart-Willcox Co., Inc Permission granted to reproduce for educational use only ... are caused by a malfunction in a system unrelated to the emission control system fuel system ignition system exhaust system computer control and electrical systems © Goodheart-Willcox Co.,... only PCV system service Evaporative emissions control system service Thermostatic air cleaner system service EGR system service Air injection system service Pulse air system service... use only (16 Topics) Computer-controlled emission system service Emission maintenance reminder Inspecting emission control systems Exhaust gas analyzer Emissions testing programs Vacuum