Conditioning For Sensor Testing
HINT:
Perform the operation with the engine speeds and time durations described below prior to checking the waveforms of the A/F and HO2 sensors. This is in order to activate the sensors sufficiently to obtain the appropriate inspection results.
- Connect the intelligent tester to the DLC3.
- Put the engine in inspection mode (See INSPECTION MODE PROCEDURE ).
- Start the engine and warm it up with all the accessories switched OFF, until the engine coolant temperature stabilizes.
- Run the engine at engine speed of between 2,500 RPM and 3,000 RPM for at least 3 minutes.
- While running the engine at 3,000 RPM for 2 seconds and 2,000 RPM for 2 seconds, check the waveforms of the A/F and HO2 sensors using the tester or scan tool.NOTE: The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.AIR-FUEL RATIO CHART
Case A/F Sensor (Sensor 1) Output Voltage HO2 Sensor (Sensor 2) Output Voltage Main Suspected Trouble Area 1 Injection Volume
+25%
-12.5%Injection Volume
+25%
-12.5%- Output Voltage
More than 3.35 V
Less than 3.0 VOutput Voltage
More than 0.55 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 0.55 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%- Injector
- Fuel pressure
- Gas leakage from exhaust system (Air fuel ratio extremely lean or rich)
Output Voltage
Almost no reactionOutput Voltage
Almost no reaction- Following the A/F CONTROL procedure enables technicians to check and graph the output voltages of both the A/F and HO2 sensors.
- To display the graph, enter the following menus on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2, and press the YES button and then the ENTER button followed by the F4 button.
HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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 AND/OR P0430)
- Connect the intelligent tester to the DLC3.
- Turn the ignition switch ON and turn the tester ON.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
- Read DTCs.
Result
RESULT CHARTDisplay (DTC output) Proceed to P0420 and/or P0430 A P0420 and/or P0430 and other DTCs B HINT:
If any DTCs other than P0420 or P0430 are output, troubleshoot those DTCs first.
B: GO TO DIAGNOSTIC TROUBLE CODE CHART
A: Go to next step
- PERFORM ACTIVE TEST USING INTELLIGENT TESTER (A/F CONTROL)
- Connect the intelligent tester to the DLC3.
- Put the engine in inspection mode (See INSPECTION MODE PROCEDURE ).
- Start the engine and turn the tester ON.
- Warm up the engine at engine speed of 2,500 RPM for approximately 90 seconds.
- On the tester, enter the following menus: 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 output voltages of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard
TESTER DISPLAY DIAGNOSIS PROCEDURETester Display (Sensor) Injection Volume Status Voltage AFS B1S1 or AFS B2S1 (A/F) +25 % Rich Less than 3.0 AFS B1S1 or AFS B2S1 (A/F) -12.5 % Lean More than 3.35 O2S B1S2 or O2S B2S2 (HO2) +25 % Rich More than 0.55 O2S B1S2 or O2S B2S2 (HO2) -12.5 % Lean Less than 0.4 Result
RESULT CHARTStatus AFS B1S1 or AFS B2S1 Status O2S B1S2 or O2S B2S2 A/F Condition and A/F and HO2 Sensor Conditions Misfire Main Suspected Trouble Areas Proceed to Lean/Rich Lean/Rich Normal - - Three-Way Catalytic Converter (TWC)
- Gas leakage from exhaust system
A Lean Lean/Rich A/F sensor malfunction - - A/F sensor
B Rich Lean/Rich A/F sensor malfunction May occur - A/F sensor
B Lean/Rich Lean HO2 sensor malfunction - - HO2 sensor
- Gas leakage from exhaust system
C Lean/Rich Rich HO2 sensor malfunction - - HO2 sensor
- Gas leakage from exhaust system
C Lean Lean Actual air-fuel ratio lean May occur - Extremely rich or lean actual air-fuel ratio
- Gas leakage from exhaust system
A Rich Rich Actual air-fuel ratio lean - - Extremely rich or lean actual air-fuel ratio
- Gas leakage from exhaust system
A Lean: During A/F CONTROL, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V.
Rich: During A/F CONTROL, the AFS is consistently less than 3.0 V, and the O2S is consistently more than 0.55 V. Lean/Rich: During A/F CONTROL of the ACTIVE TEST, the output voltage of the HO2 sensor alternates correctly.
B: CHECK AND REPLACE AIR FUEL RATIO SENSOR
C: CHECK AND REPLACE HEATED OXYGEN SENSOR, AND CHECK AND REPAIR EXHAUST GAS LEAKAGE
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