DTC Troubleshooting: P0420 (67)

DTC P0420:

Catalyst System Efficiency Below Threshold

• If some of the DTCs listed below are stored ar the same time as DTC P0420, troubleshoot those DTCs first, then recheck for DTC P0420.
  P0137, P0138, P0140: Secondary HO2S (Sensor 2)
  P0141: Secondary HO2S (Sensor 2) Heater
• When poor quality FUEL is used, this DTC may indicate.

1.	Turn the ignition switch ON (II).

2.	Do the DTC CLEAR in the CLEAR MENU with the HDS.

3.	Start the engine. Hold the engine speed at 3,000 rpm (min-1) with no load (in neutral) until the radiator fan comes on, then let it idle.

4.	Test-drive for about 10 minutes. Then it drives, changing the vehicle speed.

5.	Check the CATA MON TEMP in the DATA LIST with the HDS. Is it OK? YES - Go to 6. NO - Go to 3 and recheck.

6.	Test-drive under following conditions. Engine Coolant temperature more than 70°C (158°F) Transmission in 5th gear Vehicle speed between 70 km/h (44 mph) and 80 km/h (50 mph)

7.	Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS. Is it EXECUTING? YES - Go to 8. NO - Go to 6 and recheck.

8.	Test-drive continued untill a result comes on.

9.

Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS. Is it FAILED? YES - Go to 10. NO - If it is PASSED, intermittent failure, system is OK at this time. If it is EXECUTING, keep the driving condition continually untill a result comes on. If it is Out of CONDITION, go to 6 and recheck.

10.	Turn the ignition switch OFF.

11.	Replace the TWC.

12.	Turn the ignition switch ON (II).

13.	Do the ECM RESET in the CLEAR MENU with the HDS.

14.	Do the ETCS learn procedure.

15.	Start the engine. Hold the engine speed at 3,000 rpm (min-1) with no load (in neutral) untill the radiator fan comes on, then let it idle.

16.	Test-drive for about 10 minutes. Then it drives, changing the vehicle speed.

17.	Check the CATA MON TEMP in the DATA LIST with the HDS. Is it OK? YES - Go to 18. NO - Go to 15 and recheck.

18.	Test-drive under following conditions. Engine Coolant temperature more than 70°C (158°F) Transmission in 5th gear Vehicle speed between 70 km/h (44 mph) and 80 km/h (50 mph)

19.	Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS. Is it EXECUTING? YES - Go to 20. NO - Go to 18 and recheck.

20.	Test-drive continued untill a result comes on.

21.	Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS. Are any Temporary DTCs or DTCs indicated? YES - Go to the indicated DTC troubleshooting.n NO - Go to 22.

22.	Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS. Is it PASSED? YES - Troubleshooting is complete.n NO - If it is FAILED, check the fuel quality. If it is EXECUTING, keep the driving condition continually untill a result comes on. If it is Out of CONDITION, go to 18 and recheck.