Typical Enabling Conditions
P0037 AND P0057: (CASE 1)
| All of the following conditions are met | - |
| Battery voltage | 10.5 V or higher |
| Engine | Running |
| Starter | Off |
| Catalyst active air fuel ratio control | Not operating |
| Time after heater on | 10 seconds or more |
| Learned heater off current operation | Completed |
| Learned heater off current operation | Succeeded |
| Heated oxygen sensor heater high current fail (P0038, P0058) | Not detected |
| Heater on current - Learned heater off current | 0.15 A or less |
| Command to heater output | On |
P0037 AND P0057: (CASE 2)
| All of the following conditions are met | - |
| Battery voltage | 10.5 V or higher |
| Engine | Running |
| Starter | Off |
| Catalyst active air fuel ratio control | Not operating |
| Time after heater on | 10 seconds or more |
| Learned heater off current operation | Completed |
| Heated oxygen sensor heater high current fail (P0038, P0058) | Not detected |
| Heater off current | Higher than 3.5 A |
| Heater current detected by heater monitor IC | 4 A or higher |
P0038 AND P0058
| Monitor runs whenever the following DTCs are not stored | None |
| All of the following conditions are met | - |
| Battery voltage | 10.5 V or higher |
| Engine | Running |
| Starter | Off |
| Catalyst active air fuel ratio control | Not operating |
| Time after heater on | 10 seconds or more |
| Learned heater off current operation | Completed |
P0141 AND P0161
| All of the following conditions are met | - |
| Heated oxygen sensor heater circuit fail (P0037, P0038, P0057, P0058, P102D and P105D) | Not detected |
| Battery voltage | 10.5 V or higher |
| Fuel cut | Off |
| Time after fuel cut on to off | 30 seconds or more |
| Accumulated heater on time | 100 seconds or more |
| Learned heater off current operation | Completed |
| Duration that heated oxygen sensor impedance is less than 15 kΩ | 2 seconds or more |
P102D AND P105D
| All of the following conditions are met | - |
| Battery voltage | 10.5 V or higher |
| Engine | Running |
| Starter | Off |
| Catalyst active air fuel ratio control | Not operating |
| Time after heater on | 10 seconds or more |
| Learned heater off current operation | Completed |
| Heated oxygen sensor heater low current fail (P0037, P0057) | Not detected |
| Heated oxygen sensor heater high current fail (P0038, P0058) | Not detected |