Inspection Procedure
HINT:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
- CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420)
- Connect the intelligent tester to the DLC3.
- Turn the ignition switch ON and turn the tester ON.
- Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
- Read DTCs.
Result
RESULTDisplay (DTC Output) Proceed To P0420 A P0420 and other DTCs B HINT:
If any DTCs other than P0420 are output, troubleshoot those DTCs first.
B: GO TO DTC CHART
A: Go TO NEXT STEP.
- PERFORM ACTIVE TEST USING INTELLIGENT TESTER (A/F CONTROL)
- Connect the intelligent tester to the DLC3.
- Start the engine and turn the tester ON.
- Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
- On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
- Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
- Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2) displayed on the tester.
Result: A/F sensor reacts in accordance with increases and decreases in fuel injection volume:
+25 % = Rich output: Less than 3.0 V
-12.5 % = Lean output: More than 3.35 V
NOTE: The A/F sensor has an output delay of a few seconds and the HO2 sensor has a maximum output delay of approximately 20 seconds.A/F SENSOR (SENSOR 1)/(SENSOR 2) OUTPUT VOLTAGECase A/F Sensor (Sensor 1) Output Voltage HO2 Sensor (Sensor 2) Output Voltage Main Suspected Trouble Areas 1 Injection Volume
+25 %
-12.5 %Injection Volume
+25 %
-12.5 %- Catalyst
- Exhaust gas leak
Output Voltage age
More than 3.35 V
Less than 3.0 VOutput Voltage
More than 0.5 V
Less than 0.4 V2 Injection Volume
+25 %
-12.5 %Injection Volume
+25 %
-12.5 %- A/F sensor
- A/F sensor heater
- A/F sensor circuit
Output Voltage
Almost
no reactionOutput Voltage
More than 0.5 V
Less than 0.4 V3 Injection Volume
+25 %
-12.5 %Injection Volume
+25 %
-12.5 %- HO2 sensor
- HO2 sensor heater
- HO2 sensor circuit
Output Voltage
More than 3.35 V
Less than 3.0 VOutput Voltage
Almost
no reaction4 Injection volume
+25 %
-12.5 %Injection Volume
+25 %
-12.5 %Extremely rich or lean actual air-fuel ratio - Injector
- Fuel pressure
- Gas leakage from exhaust system
Output Voltage
Almost
no reactionOutput Voltage
Almost
no reactionFollowing the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1 S1 and O2S B1 S2; then press the YES button and then the ENTER button followed by the F4 button.
Result
RESULTResult Proceed To Case 1 A Case 2 B Case 3 C Case 4 D
B: REPLACE AIR-FUEL RATIO SENSOR
C: Go to step 4
D: CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR-FUEL RATIO, REPLACE FAULTY AREA AND Go TO NEXT STEP.
A: Go TO NEXT STEP.
- CHECK FOR EXHAUST GAS LEAKAGE
OK: No gas leakage.
NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK: REPLACE THREE-WAY CATALYTIC CONVERTER (BOTH FRONT AND REAR CATALYSTS (FRONT EXHAUST PIPE))
- CHECK FOR EXHAUST GAS LEAKAGE
OK: No gas leakage.
NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK: REPLACE HEATED OXYGEN SENSOR