P0420
DTC P0420: Catalytic System Efficiency Below ThresholdNOTE: 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 heated oxygen sensor (secondary HO2S) (Sensor 2)
P0141: Secondary HO2S (Sensor 2) heater
1. Reset the ECM with the HDS, then continue to steps 2 through 5 to reset the readiness code.
2. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on.
3. Drive for about 10 minutes without stopping on a highway or freeway. Your speed can vary.
4. With the CVT in D position, M/T in 4th gear, drive at a steady speed between 50 - 62 mph (80 - 100km/h) for 30 seconds.
5. Repeat step 4 three times. Between each repetition, decelerate with the throttle completely closed for 1 - 2 seconds. If the engine is stopped during this part of the procedure, repeat steps 3, 4, and 5.
6. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0420 indicated?
YES - Check the TWC. If necessary, replace the TWC.
NO - Check for readiness code completion. If the readiness code is complete, it was a intermittent failure, and system is OK at this time. If the readiness code is incomplete, repeat steps 2 through 5.