DTC Troubleshooting: P0420, P0430 (V6) - Honda Accord CR/CT 2012-2017

DTC Troubleshooting: P0420, P0430

DTC P0420: Rear Bank Catalyst System Efficiency Below Threshold (Bank 1)
DTC P0430: Front Bank Catalyst System Efficiency Below Threshold (Bank 2)

NOTE:

Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

If some of the DTCs listed below are stored at the same time as DTC P0420 and/or P0430^*, troubleshoot them first, then recheck for DTC P0420 and/or P0430^*.

?	P0137, P0138, P0157, P0158, P2270, P2272: Secondary HO2S (Sensor 2)
?	P0141, P0161: Secondary HO2S (Sensor 2) heater
?	P0300: Random misfire
?	P0301, P0302, P0303, P0304, P0305, P0306: No. 1, No. 2, No. 3, No. 4, No. 5, No. 6 cylinder misfire detected

Poor quality fuel may cause this DTC.

Information marked with an asterisk (*) applies to the front bank (Bank 2).

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0420 Rear Bank Catalyst System Efficiency Below Threshold (Bank 1)
P0430 Front Bank Catalyst System Efficiency Below Threshold (Bank 2)

PGM-FI system check 1:

PGM-FI system check 1

?1.	Press the engine start/stop button to select the ON mode.

?2.	Clear the DTC with the HDS.

?3.	Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.

?4.

Test-drive under these conditions:

	Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
	A/T in D, M/T in 4th
	Vehicle speed between 45?75 mph (70?120 km/h) for 5 minutes or more with cruise control set
	Vehicle speed between 55?75 mph (90?120 km/h) for 10 seconds, then decelerate (with the throttle fully closed). Repeat this three or more times
	Maintain the vehicle speed at 55 mph (88 km/h) for 4 minutes or more with cruise control set

Signal	Current conditions
Signal	Values	Unit
ECT SENSOR 1
VEHICLE SPEED

?5.

Monitor the OBD STATUS for DTC P0420 and/or P0430^* in the DTCs MENU with the HDS.

DTC Description	OBD STATUS
P0420 Rear Bank Catalyst System Efficiency Below Threshold (Bank 1)
P0430 Front Bank Catalyst System Efficiency Below Threshold (Bank 2)

Does the HDS indicate FAILED?


	YES

Replace the WU-TWC, then do the repair verification.


	NO

If the HDS indicates EXECUTING, go to step 2. If the HDS indicates OUT OF CONDITION, meet the test condition and recheck. If the HDS indicates PASSED, intermittent failure the system is OK at this time.

PGM-FI system check 2:

PGM-FI system check 2

?1.	Continue test-drive until a result comes on.

?2.

Monitor the OBD STATUS for DTC P0420 and/or P0430^* in the DTCs MENU with the HDS.

DTC Description	OBD STATUS
P0420 Rear Bank Catalyst System Efficiency Below Threshold (Bank 1)
P0430 Front Bank Catalyst System Efficiency Below Threshold (Bank 2)

Does the HDS indicate FAILED?


	YES

Replace the WU-TWC, then do the repair verification.


	NO

If the HDS indicates PASSED, intermittent failure, the system is OK at this time. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, meet the test condition and recheck.

Repair verification (OBD STATUS check):

?1.	Press the engine start/stop button to select the ON mode.

?2.	Reset the PCM with the HDS.

?3.	Do the PCM idle learn procedure.

?4.	Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.

?5.

Test-drive under these conditions:

	Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
	A/T in D, M/T in 4th
	Vehicle speed between 45?75 mph (70?120 km/h) for 5 minutes or more with cruise control set
	Vehicle speed between 55?75 mph (90?120 km/h) for 10 seconds, then decelerate (with the throttle fully closed). Repeat this three or more times
	Maintain the vehicle speed at 55 mph (88 km/h) for 4 minutes or more with cruise control set

Signal	Current conditions
Signal	Values	Unit
ECT SENSOR 1
VEHICLE SPEED

?6.

Monitor the OBD STATUS for DTC P0420 and/or P0430^* in the DTCs MENU with the HDS.

DTC Description	OBD STATUS
P0420 Rear Bank Catalyst System Efficiency Below Threshold (Bank 1)
P0430 Front Bank Catalyst System Efficiency Below Threshold (Bank 2)

Does the HDS indicate PASSED, FAILED, EXECUTING, or OUT OF CONDITION?


	PASSED (P0420)

Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting. ?


	PASSED (P0430)

Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting. ?


	FAILED (P0420)

Go to step 1 and recheck.


	FAILED (P0430)

Go to step 1 and recheck.


	EXECUTING

Keep the test condition until a result comes on.


	OUT OF CONDITION

Meet the test condition, and check the OBD STATUS again.