DTC P0420
Precautions: General safety (00)
DTC Detecting Condition and Trouble Area
| DTC detecting condition | Trouble area |
|---|---|
|
P0420: Catalyst System Efficiency below Threshold The calculated degradation index is below specified value. (3 D/C detection logic) |
•Exhaust system
•HO2S-1 and/or its circuit •HO2S-2 and/or its circuit •TWC •ECM |
Circuit Diagram
| [A]: | ECM connector (View: [a]) | 2. | TWC | 4. | ECM |
| 1. | HO2S-1 | 3. | HO2S-2 |
DTC Confirmation Procedure
WARNING:
If you do not select a suitable route and take proper precautions when performing a road test, an accident can occur.
•Select a level road with no traffic to minimize the risk of accident.
•Perform the test extremely carefully.
•Perform the road test using 2 persons, a driver and a tester.
•Perform the test extremely carefully.
•Perform the road test using 2 persons, a driver and a tester.
NOTE:
•Check that the following conditions are met in this “DTC Confirmation Procedure”.
—A/F feedback (closed loop) control is activated.
—ECT at engine start > –9 °C (16 °F)
•Check that the following DTCs are not detected in this “DTC Confirmation Procedure”.—ECT at engine start > –9 °C (16 °F)
—HO2S-1 (P0131, P0132, P0133 and P0134)
—HO2S-2 (P0137, P0138, P0140 and P2271)
—HO2S-2 (P0137, P0138, P0140 and P2271)
1)Warm up engine to normal operating temperature.
2)Drive vehicle at 60 to 100 km/h (37 to 62 mile/h) constantly for 10 min. or more at 6th gear (M/T model) or D range (A/T model). (Keep throttle valve opening constant in this step.)
3)Check whether catalyst readiness / monitoring test has completed or not using scan tool. If catalyst readiness / monitoring test has not completed, check vehicle conditions (environmental) and repeat Step 2) – 3).
DTC Troubleshooting
| Step | Action | Yes | No |
|---|---|---|---|
| 1 |
Was “Engine and Emission Control System Check” performed?
|
Go to Step 2.
|
|
| 2 |
DTC check
1)Check DTC.
Is there DTC(s) detected other than P0420?
|
Go to troubleshooting for applicable DTC.
|
Go to Step 3.
|
| 3 |
Exhaust system check
1)Check exhaust system for leakage, damage and looseness.
Is check result OK?
|
Go to Step 4.
|
Repair or replace defective parts.
|
| 4 |
HO2S-2 circuit check
1)Check HO2S-2 signal and ground circuits according to Step 3 under DTC P0137 / P0138 / P0140:K14C.
Is check result OK?
|
Go to Step 5.
|
Repair or replace defective wire harness.
|
| 5 |
HO2S-1 signal circuit check
1)Check HO2S-1 signal circuit according to Step 3 under DTC P0131 / P0132:K14C.
Is check result OK?
|
Go to Step 6.
|
Repair or replace defective wire harness.
|
| 6 |
DTC recheck
1)Replace catalytic converter.
2)Perform “DTC Confirmation Procedure”.
Is DTC P0420 still detected?
|
Go to Step 7.
|
End.
|
| 7 |
DTC recheck
1)Replace HO2S-2.
2)Check DTC.
Is DTC P0420 still detected?
|
Go to Step 8.
|
End.
|
| 8 |
DTC recheck
1)Replace HO2S-1.
2)Check DTC.
Is DTC P0420 still detected?
|
Replace ECM and recheck DTC.
|
End.
|