DTC Troubleshooting: P0420 (67) (European M/T)

DTC Troubleshooting: P0420 (67)

DTC P0420:

Catalyst System Efficiency Below Threshold

NOTE:

If some of the DTCs listed below are stored at the same time as DTC P0420, troubleshoot those DTCs first, then recheck for DTC P0420.
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) Heater
Poor quality fuel may cause this DTC.

1.	Turn the ignition switch ON (II).

2.	Do the DTC CLEAR in the CLEAR MENU with the Honda PGM Tester or the HDS.

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

Test-drive under the following conditions.

Engine coolant temperature more than 70°C (158°F)
Transmission in 5th gear (A/T in D position)
Vehicle speed between 80 km/h (50 mph) and 88 km/h (55 mph) with cruise control
Drive about 2 minutes, then decelerate for at least 4 seconds with the throttle completely closed, then accelerate to 88 km/h (55 mph) for 20 minutes with cruise control

5.	Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the Honda PGM Tester or the HDS. Is it EXECUTING? YES - Go to 6. NO - Go to 4 and recheck.

6.	Continue test driving until a result comes on.

Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the Honda PGM Tester or the HDS.

Is it FAILED?

YES - Go to 8.

NO - If it is PASSED, intermittent failure, system is OK at this time. If it is EXECUTING, keep driving condition continually until a result comes on. If it is Out of CONDITION, Go to 4 and recheck.

8.	Turn the ignition switch OFF.

9.	Replace the three way catalytic converter (TWC).

10.	Turn the ignition switch ON (II).

11.	Do the ECM/PCM RESET in the CLEAR MENU with the Honda PGM Tester or the HDS.

12.	Do the ECM/PCM idle learn procedure.

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

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

15.	Check the CATA MON TEMP in the DATA LIST with the Honda PGM Tester or the HDS. Is it OK? YES - Go to 16. NO - Go to 13 and recheck.

16.

Test-drive under the following conditions.

Engine coolant temperature more than 70°C (158°F)
Transmission in 5th gear (A/T in D position)
Vehicle speed between 80 km/h (50 mph) and 88 km/h (55 mph) with cruise control
Drive about 2 minutes, then decelerate for at least 4 seconds with the throttle completely closed, then accelerate to 88 km/h (55 mph) for 20 minutes with cruise control

17.	Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the Honda PGM Tester or the HDS. Is it EXECUTING? YES - Go to 18. NO - Go to 16 and recheck.

18.	Continue test driving until a result comes on.

19.	Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM Tester or the HDS. Are any Temporary DTCs or DTCs indicated? YES - Go to indicated DTCs troubleshooting.n NO - Go to 20.

20.

Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the Honda PGM Tester or the HDS.

Is it PASSED?

YES - Troubleshooting is complete.n

NO - If it is FAILED, check the fuel quality. If it is EXECUTING, keep driving condition continually until a result comes on. If it is Out of CONDITION, go to 13 and recheck.