P2423

DTC P2423: HC Absorber (HC Trap Catalyst) Efficiency Below Threshold [California]

TECHNICAL DESCRIPTION
After the fuel cut-off during the deceleration, the rich control is performed. Depending on the point of time when the catalyst releases oxygen which is temporarily absorbed by the lean control, the HC absorber (HC trap catalyst) within center exhaust pipe is judged on its deterioration in performance.

DESCRIPTIONS OF MONITOR METHODS
When the difference in the switching time into the rich control is below the specified time between the heated (rear) oxygen sensor and the heated oxygen sensor (3rd), it is judged that a malfunction exists.

MONITOR EXECUTION
Once per driving cycle

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 (3rd) monitor
- Heated oxygen sensor heater (front) monitor
- Heated oxygen sensor heater (rear) monitor
- Heated oxygen sensor heater (3rd) 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 speed is lower than 1,500 r/min [M/T] or 1,313 r/min [CVT].
- Volumetric efficiency is lower than 25 percent [M/T] or 35 percent [CVT].
- The throttle valve is closed.
- Barometric pressure is higher than 76 kPa (22.4 in.Hg).
- Intake air temperature is higher than -10 °C (14 °F).
- The accumulative mass airflow is higher than 2,900 g.
- The fuel shut-off mode continues for 3 seconds or more.
- After the fuel shut-off mode is terminated, the output voltage of the heated oxygen sensor (3rd) is 0.2 volt or less for 0.5 seconds.

Judgment Criterion
- After the output voltage of the heated oxygen sensor (rear) reaches 0.5 volt, the output voltage of the heated oxygen sensor (3rd) reaches 0.5 volt within 1.5 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 11. OBD-II Drive Cycle

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- HC trap catalyst deterioration within center exhaust pipe.
- 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. Replace the center exhaust pipe.

1. Replace the center exhaust pipe.
2. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 11. OBD-II Drive Cycle
3. Check the diagnostic trouble code (DTC).

Q: Is DTC P2423 set?

YES : Replace the ECM. When the ECM is replaced, register the ID code.

NO : The inspection is complete.