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DTC P014D: Linear Air-Fuel Ratio Sensor Circuit Slow Response - Lean to Rich
 
 
 
 
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
  • When the average of the difference between the response times of the rich side and the lean side of the linear air-fuel ratio sensor during the monitoring time becomes equal to or higher than the predetermined value, the DTC is set as the linear air-fuel ratio sensor deterioration.
 
 
MONITOR EXECUTION
  • Continuous
 
 
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
  • Barometric pressure sensor
  • Throttle position sensor
  • Fuel tank pressure sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Conditions
  • Engine speed is between 1,094 and 3,500 r/min.
  • Volumetric efficiency is between 35 and 85 percent.
  • Mass airflow sensor output is 1.2 g/sec or more.
  • Engine coolant temperature is more than 60°C (140°F).
  • Under the closed loop air/fuel control.
  • The accelerator pedal is depressed.
  • Short-term fuel trim is between -25 and +25 percent.
  • More than 8 seconds have passed after the above mentioned conditions have been met.
  • During the drive cycle, the ECM performs monitoring with the accumulated total time of 10 seconds, 3 times.
Judgment Criteria
  • The average response time ratio (to rich time/to lean time) is more than specified value.
  • The amount of compensated air/fuel ratio based on the heated oxygen sensor (rear) is out of specified amount.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnosis Function - OBD-II Drive Cycle - Pattern 4 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Linear air-fuel ratio sensor failed.

 
 
DIAGNOSIS
STEP 1. Test the OBD-II drive cycle.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn on the power supply mode of the electric motor switch and delete the DTC.
(3) Carry out the test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 4 .
(4) Check the diagnostic trouble code (DTC).
Is DTC P014D set?
Replace the linear air-fuel ratio sensor. Then go to Step 2.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/ Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 2. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 4 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P014D set?
Retry the troubleshooting.
The inspection is complete.