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 heated oxygen sensor (front).
If the heated oxygen sensor (front) has deteriorated, corrections will be made by the heated oxygen sensor (rear).

DESCRIPTIONS OF MONITOR METHODS

When an abnormality exists in the heated oxygen sensor (front), 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 heated oxygen sensor (front) is normal.

MONITOR EXECUTION

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

Heated oxygen sensor (front) monitor
Heated oxygen sensor (rear) monitor
Heated oxygen sensor (front) heater monitor
Heated oxygen sensor (rear) heater monitor
Heated oxygen sensor (front) inactive monitor
Heated oxygen sensor offset voltage monitor
Misfire monitor
Fuel system monitor
Air/fuel ratio feedback 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).
Under the closed loop air/fuel control.
More than 90 seconds have passed since the engine starting sequence was completed.
Mass airflow sensor output is more than 5 g/sec.

Judgement 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

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

Heated oxygen sensor (front) 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).

caution

To 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.

Q. Is the diagnostic trouble code other than P2096 set?

Refer to, Diagnostic Trouble Code Chart

Go to Step 2.

STEP 2. Replace the heated oxygen sensor (front).

(1)Replace the heated oxygen sensor (front).

(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).

Q. 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).

Q. 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).

Q. Is DTC P2096 set?

	Replace the ECM. When the ECM is replaced, register the ID code. Refer to GROUP 42B, Diagnosis - ID Code Registration Necessity Judgment Table <Vehicles with KOS> or GROUP 42C, Diagnosis - ID Codes Registration Judgment Table <Vehicles with WCM> .

	The inspection is complete.