DTC Troubleshooting

DTC TROUBLESHOOTING PROCEDURES

Step	Action	YES	NO
1	Was "Engine and Emission Control System Check" performed?	Go to Step 2.	Go to ENGINE AND EMISSION CONTROL SYSTEM CHECK .
2	HO2S signal check Connect scan tool with ignition switch turned OFF. Warm up engine to normal operating temperature and keep it at 2000 r/min. for 60 sec. Repeat racing engine (Repeat depressing accelerator pedal 5 to 6 times continuously to enrich A/F mixture and take foot off from pedal to enlean it). Check for HO2S output voltage displayed on scan tool. Does HO2S output voltage indicates approx. 0 V for a few seconds, then approx. 0.7 V?	Intermittent trouble. Check for intermittent referring to INTERMITTENT AND POOR CONNECTION INSPECTION .	Go to Step 3.
3	Intake system and exhaust system for leakage check Check intake system and exhaust system for leakage. Are intake system and exhaust system in good condition?	Go to Step 4.	Repair or replace defective parts.
4	Fuel injectors and its circuit check Check each fuel injectors referring to FUEL INJECTOR INSPECTION . Is check result satisfactory?	Go to Step 5.	Faulty injector(s) or its circuit.
5	HO2S circuit check Disconnect connector from HO2S and ECM with ignition switch turned OFF. Check for proper terminal connection to HO2S connector and ECM connector. If connections are OK, check that HO2S circuit is as follows. Wiring harness resistance of each "Signal circuit of HO2S", "Ground circuit of HO2S" and "Control circuit of HO2S heater" is less than 1 Ω. Insulation resistance between "Signal circuit of HO2S" and vehicle body ground is infinity. Insulation resistance of wire harness is infinity between "Signal circuit of HO2S" terminal and each other terminal at HO2S connector. Circuit voltage between "Signal circuit of HO2S" and vehicle body ground is 0 V with ignition switch turned ON. Are they in good condition?	Go to Step 6.	Repair or replace defective wiring harness / connector.
6	HO2S heater check Check heater resistance of HO2S referring to HEATED OXYGEN SENSOR (HO2S) HEATER ON-VEHICLE INSPECTION . Is HO2S heater in good condition?	Go to Step 7.	Replace HO2S.
7	A/F sensor circuit check Disconnect connectors from A/F sensor with ignition switch turned OFF. Check for proper terminal connection to A/F sensor connector and ECM connector. If connections are OK, check that A/F sensor circuit is as follows. Wiring harness resistance of each "Signal (+) circuit of A/F sensor", "Signal (-) circuit of A/F sensor", "Control circuit of A/F sensor heater" and "Control ground circuit of A/F sensor heater" is less than 1 Ω. Is it in good condition?	Go to Step 8.	Repair or replace defective wiring harness / connector.
8	A/F sensor check Check for A/F sensor referring to AIR FUEL RATIO (A/F) SENSOR ON-VEHICLE INSPECTION . Is check result satisfactory?	Go to Step 9.	Replace A/F sensor.
9	Engine mechanical systems check Check engine mechanical systems. Engine compression: Refer to COMPRESSION CHECK . Valve lash: Refer to VALVE LASH (CLEARANCE) INSPECTION . Intake & exhaust valve: Refer to VALVES AND VALVE GUIDES INSPECTION . Is check result satisfactory?	Replace HO2S and recheck. If this DTC is detected again, replace A/F sensor.	Repair or replace defective parts.