Air Fuel Ratio (A/F) Sensor Inspection
AIR FUEL RATIO (A/F) SENSOR INSPECTION [LF]
NOTE:
- Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. Description and Operation
A/F sensor Current Inspection
1. Warm up the engine to normal operating temperature.
2. Using the M-MDS, monitor the following:
- Vehicle speed (PID: VSS)
- Engine speed (PID: RPM)
- A/F sensor current (PID: O2S11)
3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.
4. Verify that the A/F sensor current (PID: O2S11) is 0.25 mA or more while decelerating as shown in the figure.
- If not within the specification, inspect the A/F sensor for an open or short circuit. Air Fuel Ratio (A/F) Sensor Removal/Installation Then if there is no malfunction in the wiring harness, replace the A/F sensor. Air Fuel Ratio (A/F) Sensor Removal/Installation
A/F sensor Heater Resistance Inspection
1. Disconnect the A/F sensor connector.
2. Measure the resistance between A/F sensor terminals C and D.
- If not within the specification, replace the A/F sensor. Air Fuel Ratio (A/F) Sensor Removal/Installation
A/F sensor heater resistance
- 1-10 ohms
A/F sensor Circuit Open/Short Inspection
1. Disconnect the PCM connector. Service and Repair
2. Disconnect the A/F sensor connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)
Open circuit
- If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
- A/F sensor terminal A and PCM terminal 2AD
- A/F sensor terminal B and PCM terminal 2Z
- A/F sensor terminal C ignition relay
- A/F sensor terminal D and PCM terminal 2BG
Short circuit
- If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- A/F sensor terminal A and power supply
- A/F sensor terminal A and body ground
- A/F sensor terminal B and power supply
- A/F sensor terminal B and body ground
- A/F sensor terminal C and body ground
- A/F sensor terminal D and power supply
- A/F sensor terminal D and body ground