DTC P0420 (1.5 L Engine)

DTC P0420  : Catalyst System Efficiency Below Threshold

NOTE: 

• Before you troubleshoot, review the general troubleshooting information .
• If some of the DTCs listed below are stored at the same time as DTC P0420, troubleshoot them first, then recheck for DTC P0420.

  P0137, P0138, P2270: Secondary HO2S (Sensor 2)

  P0141: Secondary HO2S (Sensor 2) heater

  P0300: Random misfire

  P0301, P0302, P0303, P0304: No. 1-No. 4 cylinder misfire

• Poor quality fuel may cause this DTC.

DTC (PGM-FI)

1. PGM-FI system check 1

   -1. Turn the vehicle to the ON mode.

   -2. Clear the DTC with the HDS.

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

   -4. Test-drive the vehicle under these conditions:

   • Engine coolant temperature (ECT Sensor 1) above 158 deg. F (70 deg. C)
   • CVT in D, M/T in 4th or 5th
   • Vehicle speed between 45-75 mph (70-120 km/h) for 5 minutes or more
   • 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 (90 km/h) for 4 minutes or more with cruise control set.

   Signal	Current conditions
   	Values	Unit
   ECT Sensor 1
   Vehicle Speed

   -5. Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS.

   DTC Description	OBD STATUS
   P0420 Catalyst System Efficiency Below Threshold

   Does the HDS indicate FAILED?

   YES 

   Replace the TWC .

   NO 

   If the HDS indicates EXECUTING, go to step 2. If the HDS indicates OUT OF CONDITION, meet the test conditions and recheck. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot . If the HDS indicates PASSED, intermittent failure the system is OK at this time.

2. PGM-FI system check 2

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

   -2. Monitor the OBD STATUS for DTC P0420 in the DTCs MENU with the HDS.

   DTC Description	OBD STATUS
   P0420 Catalyst System Efficiency Below Threshold

   Does the HDS indicate FAILED?

   YES 

   Replace the TWC .

   NO 

   If the HDS indicates PASSED, intermittent failure, the system is OK at this time. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot . If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, meet the test conditions and recheck.