| 1 |
Was "Engine and Emission Control System Check" performed? |
Go to Step 2. |
Go to ENGINE AND EMISSION CONTROL SYSTEM CHECK . |
| 2 |
DTC check
- Check DTC.
Is there DTC(s) other than P0420? |
Go to troubleshooting for applicable DTC. |
Go to Step 3. |
| 3 |
Exhaust system visual inspection
- Check exhaust system for leak, damage and looseness.
Is it in good condition? |
Go to Step 4. |
Repair or replace defective parts. |
| 4 |
HO2S circuit check
- Check signal and ground circuits of HO2S for high resistance referring to step 3 of DTC P0137: O2 Sensor Circuit Voltage Low (Bank 1, Sensor 2); P0138: O2 Sensor Circuit Voltage High (Bank 1, Sensor 2) EVAP-Leak-Check Model .
Are they in good condition? |
Go to Step 5. |
Repair or replace defective wire harness. |
| 5 |
A/F sensor signal circuit check
- Check A/F sensor signal circuit referring to Step 3 of DTC P0131: O2 Sensor (HO2S) Circuit Low Voltage (Bank-1 Sensor-1); P0132: O2 Sensor (HO2S) Circuit High Voltage (Bank-1 Sensor-1); P0134: O2 Sensor (HO2S) No Activity Detected (Bank-1 Sensor-1); P2195: O2 Sensor Signal Stuck Lean (Bank-1 Sensor-1); P2196: O2 Sensor Signal Stuck Rich (Bank-1 Sensor-1); P2237: O2 Sensor Positive Current Control Circuit/Open .
Are they in good condition? |
Go to Step 6. |
Repair or replace defective wire. |
| 6 |
- Replace exhaust manifold (built in TWC). Refer to EXHAUST MANIFOLD REMOVAL AND INSTALLATION
.
- Perform
DTC confirmation procedure.
Is DTC P0420 still detected? |
Go to Step 7. |
End. |
| 7 |
- Replace HO2S. Refer to A/F (AIR FUEL RATIO) SENSOR, HO2S (HEATED OXYGEN SENSOR) REMOVAL AND INSTALLATION
.
- Check DTC.
Is DTC P0420 still detected? |
Go to Step 8. |
End. |
| 8 |
- Replace A/F sensor. Refer to A/F (AIR FUEL RATIO) SENSOR, HO2S (HEATED OXYGEN SENSOR) REMOVAL AND INSTALLATION
.
- Check DTC.
Is DTC P0420 still detected? |
Substitute a known-good ECM and recheck. |
End. |