CIRCUIT OPERATION
- Power is supplied from the MFI relay to the linear air-fuel ratio sensor heater.
- The ECM terminal LHFL controls continuity to the linear air-fuel ratio sensor heater by turning the power transistor in the ECM "ON" and "OFF".
TECHNICAL DESCRIPTION
The ECM checks whether the heater current is within a specified range when the heater is energized.
DESCRIPTIONS OF MONITOR METHODS
- Linear air-fuel ratio sensor heater current is out of specified range.
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
Sensor (The sensor below is determined to be normal)
Check Conditions
- More than 220 seconds have passed since the engine starting sequence was completed.
- While the linear air-fuel ratio sensor heater is on.
- Battery positive voltage is between 11 and 16.5 volts.
- Intake air temperature is more than -10°C (14°F).
- On duty cycle of the linear air-fuel ratio sensor heater is between 3 and 97 percent.
Judgment Criterion
- The linear air-fuel ratio sensor heater current has continued to be lower than average 1.25 ampere for 10 seconds.
FAIL-SAFE AND BACKUP FUNCTION
OBD-II DRIVE CYCLE PATTERN
- Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2 .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
- Linear air-fuel ratio sensor circuit harness damage or connector damage.
- Linear air-fuel ratio sensor heater failed.
- ECM failed.