Component Location Index
DTC Troubleshooting
DTC P0420: Catalyst System Efficiency Below Threshold
NOTE:
P0137, P0138: Secondary HO2S (Sensor 2) P0141: Secondary HO2S (Sensor 2) heater
1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
4. Test-drive under these conditions:
5. Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS.
Does the screen indicate EXECUTING? YES-Go to step 6.
NO-Go to step 4 and recheck.
6. Continue test driving until a result comes on.
7. Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS.
Does the screen indicate FAILED? YES-Go to step 8.
NO-If the screen indicates PASSED, intermittent failure, the system is OK at this time. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 4 and recheck.
8. Turn the ignition switch OFF.
9. Replace the TWC.
10. Turn the ignition switch ON (II).
11. Reset the PCM with the HDS.
12. Do the PCM idle learn procedure.
13. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
14. Test-drive for about 10 minutes, varying the vehicle speed.
15. Check the CATA MONITOR CONDITION in the DATA LIST with the HDS.
Is the temperature OK? YES-Go to step 16.
NO-Go to step 13 and recheck.
16. Test-drive under these conditions:
17. Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS.
Does the screen indicate EXECUTING? YES-Go to step 18.
NO-Go to step 16 and recheck.
18. Continue test-driving until a result comes on.
19. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0420 indicated? YES-Check the fuel quality, then go to step 1.
NO-Go to step 20.
20. Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS.
Does the screen indicate PASSED? YES-Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 19, go to the indicated DTC's troubleshooting.
NO-If the screen indicates FAILED, check the fuel quality, then go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 13.
Catalytic Converter Removal/Installation
1. Lift the vehicle, and support it with jackstands.
2. Remove the A/F sensor (Sensor 1).
3. Remove the secondary HO2S (Sensor 2).
4. Remove the bolts (A), and the nuts (B).
5. Remove the bolts (C), and the covers (D).
6. Remove the TWC (E).
7. Install the parts in the reverse order of removal with new gaskets (F).