Diagnostic Procedure

STEP	INSPECTION	RESULTS	ACTION
1	INSPECT RELATED PART CONDITION Inspect the following: Electrical connections Intake air system and air cleaner element concerns: obstructions, leakage or soiling Proper maintenance schedule followed Vacuum lines for leakage or blockage Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Repeat Step 1.
1		No	Go to the next step.
2	VERIFY PCM DTC Perform the PCM DTC inspection using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST .) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE .)
2		No	Go to the next step.
3	VERIFY IF MALFUNCTION INCLUDES DRIVEABILITY Is any other driveability concern present?	Yes	Go to the applicable symptom troubleshooting. (See ENGINE CONTROL SYSTEM SYMPTOM DIAGNOSTIC INDEX .)
3		No	Go to the next step.
4	INSPECT COOLING SYSTEM FOR MALFUNCTION CAUTION: While performing this step, always operate the vehicle in a safe and lawful manner. When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later. Access the ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST .) Drive the vehicle while monitoring the ECT PID. Is the ECT PID value within the specification? (See PCM INSPECTION .)	Yes	Go to the next step.
4		No	Inspect the following: Coolant leakage Cooling fan operation Thermostat operation Repair or replace the malfunctioning part according to the inspection results.
5	INSPECT FUEL CAP Inspect the fuel-filler cap. Is there any leakage at the fuel-filler cap?	Yes	Replace the fuel-filler cap.
5		No	Go to the next step.
6	INSPECT CURRENT A/F SENSOR SIGNAL Inspect the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR INSPECTION .) Is there any malfunction?	Yes	Inspect the following: Exhaust gas leakage between exhaust manifold and A/F sensor Loose installation of A/F sensor If there is any malfunction: Repair or replace the malfunctioning part according to the inspection results. If there is no malfunction: Replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION .)
6		No	Go to the next step.
7	INSPECT IGNITION SYSTEM OPERATION Perform the Spark Test. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION .) Is a strong blue spark visible at each cylinder?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning part according to the inspection results.
8	INSPECT FUEL LINE PRESSURE Inspect the fuel line pressure. (See FUEL LINE PRESSURE INSPECTION .) Is there any malfunction?	Yes	Zero or low: Inspect the fuel pump relay and the fuel pump circuit. (See RELAY INSPECTION .) Inspect the fuel line for restriction. If there is any malfunction: Repair or replace the malfunctioning part according to the inspection results. If there is no malfunction: Replace the fuel pump unit. (Pressure regulator or fuel pump malfunction) (See FUEL PUMP UNIT REMOVAL/INSTALLATION .) High: Replace the fuel pump unit. (Pressure regulator malfunction) (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
8		No	Go to the next step.
9	DETERMINE IF MALFUNCTION CAUSE IS CHARCOAL CANISTER OR FUEL TANK VENT SYSTEM Inspect for fuel saturation inside the charcoal canister. Is there an excess amount of liquid fuel present in canister?	Yes	Replace the charcoal canister. (See CHARCOAL CANISTER REMOVAL/INSTALLATION .)
9		No	Inspect the fuel tank vent system, then go to the next step. (See FUEL TANK INSPECTION .)
10	INSPECT DEFORMED IN EXHAUST SYSTEM Visually inspect the exhaust system. Are there any deformed exhaust system parts?	Yes	Repair or replace the malfunctioning part according to the inspection results.
10		No	Go to the next step.
11	INSPECT EGR VALVE OPERATION Perform the EGR Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION .) Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results.
11		No	Go to the next step.
12	INSPECT ENGINE COMPRESSION Inspect the engine compression. (See COMPRESSION INSPECTION .) Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results.
12		No	Go to the next step.
13	DETERMINE IF MALFUNCTION IS IN TWC OR OTHER Make sure to install all removed parts. Perform the Drive Mode 03 (EGR system, A/F sensor heater, HO2S heater, A/F sensor, HO2S and TWC Repair Verification Drive Mode). (See OBD-II DRIVE MODE .) Perform the PCM DTC inspection using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST .) Is the DTC P0421:00 present?	Yes	Go to the applicable DTC inspection. (See DTC P0421:00 .)
13		No	Go to the next step.
14	INSPECT IF MALFUNCTION CAUSE IS PCV VALVE OR VALVE TIMING Inspect the PCV valve. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION .) Is there any malfunction?	Yes	Replace the PCV valve and the oil separator as a single unit, then go to the next step. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION .)
14		No	Inspect the valve timing. (See VARIABLE VALVE TIMING ACTUATOR INSPECTION .) Repair or replace the malfunctioning part according to the inspection results.
15	Verify test results. If normal, return to the diagnostic index to service any additional symptoms. (See ENGINE CONTROL SYSTEM SYMPTOM DIAGNOSTIC INDEX .) If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis. If the vehicle is repaired, troubleshooting is completed. If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.