P1420

DTC P1420: NOX Adosorptive Catalytic System Efficiency Below Threshold-'02-03 M/T models

NOTE: If some of the DTCs listed below are stored at the same time as DTC P1420, troubleshoot those DTCs first, then recheck for DTC P1420.

P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) Heater

P0143, P0144: Third HO2S (Sensor 3)
P0147: Third HO2S (Sensor 3) Heater

1. Reset the ECM.
2. Start the engine. Hold the engine at 3,000 rpm with no load (in neutral) until the radiator fan comes on.
3. Keep the engine speed at 4,000 rpm about 10 minutes.
4. Test-drive under following conditions.
- 55 - 65 mph (89 - 105 km/h) steady speed
- Transmission in 4th or 5th gear
- Until the readiness code or Temporary DTC P1420 and/or P1420 is set

5. Check for a Temporary DTC with the scan tool.

Is Temporary DTC P1420 and/or P1420 indicated?

YES - Check the NOX Adsorptive three way catalytic converter (NOX Adsorptive TWC). If necessary, replace the NOX Adsorptive TWC.

NO - Intermittent failure, system is OK at this time.