Checking Trouble Codes (DTC)
Code DTCP0420 (67-1): Neutralizer efficiency below threshold
Note: If any of the following DTCs are stored in memory at the same time as DTC P0420, check these DTCs first and then return to KDTCP0420.
P0137, P0138: Low/High Voltage in Secondary Heated Oxygen Sensor Circuit (secondary HO2S) (sensor #2)
P0141: Malfunction in the heating element circuit of the secondary heated oxygen sensor (secondary HO2S) (sensor #2)
1. Reset the ECM/PCM, then follow steps. 2-5 and reset the readiness code.
2. Start the engine. Maintain RPM at 3000 rpm (min⁻¹) without load (in Park or Neutral position), until the radiator fan comes on, then let it idle.
3. Drive your car for 10 minutes without stopping on a highway or motorway. The speed of the car may vary.
4. After shifting the automatic transmission to position D, the manual transmission to 5th gear, drive the car at a steady speed of 80-100 km/h for 30 seconds.
5. Perform step. 4 four times. Before each repetition, close the throttle completely for 1-2 seconds. If the engine stalls during this part of the procedure, proceed to step. 3 and repeat the procedure.
6. Check the temporary DTC using a scanner.
Does the scanner show a temporary DTC P0420?
Yes Check the TWC converter and replace it if necessary.
No Check the completion of the readiness code. If the readiness code is complete, it was an intermittent fault and the system is currently OK. If the readiness code is not complete, follow steps. 2-5 times again.
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