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DTC P2096: Post Catalyst Fuel Trim System too Lean
 
 
 
 
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 an abnormality exists in the linear air-fuel ratio sensor, the amount of compensated fuel injection is abnormal. When this situation continues, it is judged to be faulty.
  • If an abnormality exists in the heated oxygen sensor (rear), also it is judged to be faulty even though the linear air-fuel ratio sensor is normal.
 
 
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 monitor
  • Heated oxygen sensor (rear) monitor
  • Linear air-fuel ratio sensor heater monitor
  • Heated oxygen sensor (rear) heater monitor
  • Heated oxygen sensor offset voltage 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
  • Accelerator pedal position sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Conditions
  • Engine coolant temperature is more than 76°C (169°F).
  • The closed loop air/fuel control continues for more than 10 seconds.
  • More than 90 seconds have passed since the engine starting sequence was completed.
  • Mass airflow sensor output is more than 8 g/sec.
  • After the engine start, the accumulated time where the four conditions mentioned above are satisfied is more than 60 seconds.
Judgment Criterion
  • The amount of compensated rich air/fuel ratio is output by the heated oxygen sensor (rear). The status that the amount of compensated rich air/fuel ratio is greater than the specified amount continues for 5 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic 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.
  • Heated oxygen sensor (rear) failed.
  • Injector failed.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: V.C.I.
    • MB991827: USB Cable
    • MB991910: Main Harness A
STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the diagnostic trouble code other than P2096 set?
Refer to, Diagnostic Trouble Code Chart .
Go to Step 2.
 
STEP 2. Replace the linear air-fuel ratio sensor.
(1) Replace the linear air-fuel ratio sensor.
(2) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(3) Check the diagnostic trouble code (DTC).
Is DTC P2096 set?
Go to Step 3.
The inspection is complete.
 
STEP 3. Replace the heated oxygen sensor (rear).
(1) Replace the heated oxygen sensor (rear).
(2) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(3) Check the diagnostic trouble code (DTC).
Is DTC P2096 set?
Go to Step 4.
The inspection is complete.
 
STEP 4. Replace the injector.
(1) Replace the injector.
(2) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(3) Check the diagnostic trouble code (DTC).
Is DTC P2096 set?
Replace the ECM (Refer to, Removal and Installation ).
The inspection is complete.