DTC P0420
Precautions: General safety (00)
DTC Detecting Condition and Trouble Area
| DTC detecting condition | Trouble area |
|---|---|
|
P0420: Catalyst System Efficiency below Threshold Average amplitude of HO2S-2 signal is more than specified valve under specified vehicle condition. (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 with 2 persons, a driver and a tester.
•Perform the test extremely carefully.
•Perform the road test with 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 heater (P0030, P0031 and P0032)
—HO2S-2 heater (P0036, P0037 and P0038)
—TP sensor (P0122, P0123, P0222 and P0223)
—HO2S-1 (P0130, P0131, P0132, P0133 and P0134)
—HO2S-2 (P0137, P0138, P0140 and P2271)
—Fuel trim system (P0171 and P0172)
—Cylinder misfire detected (P0300)
—EVAP canister purge valve (P0443, P0458 and P0459)
—HO2S-2 heater (P0036, P0037 and P0038)
—TP sensor (P0122, P0123, P0222 and P0223)
—HO2S-1 (P0130, P0131, P0132, P0133 and P0134)
—HO2S-2 (P0137, P0138, P0140 and P2271)
—Fuel trim system (P0171 and P0172)
—Cylinder misfire detected (P0300)
—EVAP canister purge valve (P0443, P0458 and P0459)
1)Warm up engine to normal operating temperature.
2)With engine speed at 2,600 to 3,500 rpm, drive vehicle at 100 to 120 km/h (62 to 75 mile/h) constantly for 5 min. or more at 5th 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:M16A.
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:M16A.
Is check result OK?
|
Go to Step 6.
|
Repair or replace defective wire harness.
|
| 6 |
DTC recheck
1)Replace exhaust manifold (incorporating TWC).
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.
|