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.
- Start the engine and warm it up with all the accessories switched OFF, until the engine coolant temperature stabilizes.
- Run the engine at an 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.
HINT:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using the intelligent tester.
- 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 B1S1 and OS2 B1S2) 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 (Sensor) | Injection Volumes | Status | Voltages |
|---|---|---|---|
| AFS B1S1 (A/F) | +25% | Rich | Less than 3.0 |
| AFS B1S1 (A/F) | -12.5% | Lean | More than 3.35 |
| O2S B1S2 (HO2) | +25% | Rich | More than 0.55 |
| O2S B1S2 (HO2) | -12.5% | Lean | Less than 0.4 |
| Case | A/F Sensor (sensor 1) Output Voltage | HO2S Voltage (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 V |
Output Voltage More than 0.55 V Less than 0.4 V |
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| 2 | Injection Volume +25% -12.5% |
Injection Volume +25% -12.5% |
|
||
| Output Voltage Almost no reaction |
Output Voltage More than 0.55 V Less than 0.4 V |
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| 3 | Injection Volume +25% -12.5% |
Injection Volume +25% -12.5% |
|
||
| Output Voltage More than 3.35 V Less than 3.0 V |
Output Voltage Almost no reaction |
||||
| 4 | Injection volume +25% -12.5% |
Injection Volume +25% -12.5% |
|
||
| Output Voltage Almost no reaction |
Output Voltage Almost no reaction |
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- Following 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 B1S1 and O2S B1S2, and press the YES button and then the ENTER button followed by the F4 button.
HINT:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. 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)
- 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
RESULT CHARTDisplay (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 BY 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 B1S1 and O2S B1S2) 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 voltage
VOLTAGE CHARTTester Display (Sensor) Injection Volumes Status Voltages AFS B1S1 (A/F) +25% Rich Less than 3.0 AFS B1S1 (A/F) -12.5% Lean More than 3.35 O2S B1S2 (HO2) +25% Rich More than 0.55 O2S B1S2 (HO2) -12.5% Lean Less than 0.4 Result
RESULT CHARTStatus AFS B1S1 Status O2S B1S2 A/F Condition and A/F and HO2 Sensors Condition Misfires 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 - - 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 rich - - 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.
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.
NOTE: Replace both the front and rear catalysts (front exhaust pipe).NG : REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK : REPLACE EXHAUST MANIFOLD CONVERTER