CIRCUIT OPERATION
The linear air-fuel ratio sensor and the ECM are connected by the following three lines to detect the air-fuel ratio.
- The line between the linear air-fuel ratio sensor and the ECM terminal LPFL detects the air-fuel ratio.
- The auxiliary line between the linear air-fuel ratio sensor and the ECM terminal LSFL detects the air-fuel ratio.
- The line between the linear air-fuel ratio sensor and the ECM terminal LEFL is connected to ground.
TECHNICAL DESCRIPTION
- The ECM effects air/fuel ratio feedback control in accordance with the signals from the linear air-fuel ratio sensor.
- If the linear air-fuel ratio sensor has deteriorated, corrections will be made by the heated oxygen sensor (rear).
DESCRIPTIONS OF MONITOR METHODS
- If one of the three line voltages is excessively low or if all the three line voltages are excessively low, the DTC is set as a malfunction.
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
- Linear air-fuel ratio sensor heater monitor
- Misfire monitor
- Fuel system monitor
Sensor (The sensor below is determined to be normal)
- Mass airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor 1
- Barometric pressure sensor
- Throttle position sensor
- Accelerator pedal position sensor
Check Conditions
- Battery positive voltage is between 10 and 16.5 volts.
- More than 40 seconds have passed since the engine starting sequence was completed.
Judgment Criterion
- The pumping circuit voltage is be lower than 2 volts for 2 seconds.
or
- The reference circuit voltage is be lower than 1.2 volt for 2 seconds.
or
- The negative circuit voltage is be lower than 1.2 volt for 2 seconds.
FAIL-SAFE AND BACKUP FUNCTION
- Does not control air-fuel ratio closed loop.
OBD-II DRIVE CYCLE PATTERN
- Refer to Diagnosis Function - OBD-II Drive Cycle - Pattern 1 .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
- Linear air-fuel ratio sensor failed.
- Shorted linear air-fuel ratio sensor circuit, or connector damage.
- ECM failed.