DTC Troubleshooting

Control System DTCs

DTC Troubleshooting: P0141

DTC P0141 : Secondary HO2S (Sensor 2) Heater Circuit Malfunction

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information How To Troubleshoot The Fuel And Emissions Systems.

1. Problem verification:

Problem verification
-1. Turn the ignition switch to ON (II).

-2. Clear the DTC with the HDS.

-3. Start the engine, and let it idle.

-4. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0141 indicated?
-YES- The failure is duplicated. Go to step 2.
-NO- Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at secondary HO2S (Sensor 2), and the ECM.

2. Shorted wire check (IG1_ACG line):

Shorted wire check (IG1_ACG line)
-1. Turn the ignition switch to LOCK (0).

-2. Check the following fuse.





Is the fuse OK?
-YES- The IG1_ACG wire is not shorted. Go to step 3.
-NO- Repair a short in the IG1_ACG wire between secondary HO2S (Sensor 2) and the No. B2 (15 A) fuse. Also replace the No. B2 (15 A) fuse, then do the repair verification.

3. Secondary HO2S (Sensor 2) internal heater resistance check:

Secondary HO2S (Sensor 2) internal heater resistance check
-1. Disconnect the following connector.





-2. At the sensor side, measure the resistance between test points 1 and 2.









Is there 5.4-7.3 Ohms at room temperature?
-YES- Go to step 4.
-NO- Replace secondary HO2S (Sensor 2) Secondary HO2S Removal and Installation, then do the repair verification.

4. Secondary HO2S (Sensor 2) internal circuit check:

Secondary HO2S (Sensor 2) internal circuit check
-1. At the sensor side, check for continuity under the following conditions.














Is there continuity?
-YES- Replace secondary HO2S (Sensor 2) Secondary HO2S Removal and Installation, then do the repair verification.
-NO- Go to step 5.

5. Determine possible failure area (SO2HTC line, others):

Determine possible failure area (SO2HTC line, others)
-1. Turn the ignition switch to ON (II).

-2. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- Go to step 6.
-NO- Go to step 7.

6. Shorted wire check (SO2HT line):

Shorted wire check (SO2HT line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connector.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short in the SO2HT wire between the ECM (B4) and secondary HO2S (Sensor 2), then do the repair verification.
-NO- The SO2HT wire is OK. Update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then do the repair verification.

7. Open wire check (IG1_ACG line):

Open wire check (IG1_ACG line)
-1. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- The IG1_ACG wire is OK. Go to step 8.
-NO- Repair an open in the IG1_ACG wire between the No. B2 (15 A) fuse and secondary HO2S (Sensor 2), then do the repair verification.

8. Open wire check (SO2HT line):

Open wire check (SO2HT line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connector.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The SO2HT wire is OK. Update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then do the repair verification.
-NO- Repair an open in the SO2HT wire between the ECM (B4) and secondary HO2S (Sensor 2), then do the repair verification.

Repair verification (OBD STATUS check):

-1. Turn the ignition switch to LOCK (0).

-2. Reconnect all connectors.

-3. Turn the ignition switch to ON (II).

-4. Reset the ECM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-5. Do the ECM idle learn procedure. ECM/PCM Idle Learn Procedure

-6. Monitor the OBD STATUS for DTC P0141 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED, FAILED, or NOT COMPLETED?
-PASSED- Troubleshooting is complete. If the ECM was substituted, replace the original ECM Service and Repair. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.
-FAILED- Go to step 1 and recheck. If the ECM was updated, substitute a known-good ECM Service and Repair, then check the OBD STATUS again.
-NOT COMPLETED - Meet the test condition, and check the OBD STATUS again.