2.12.7.25 DTC P0141 

1. DTC 

description: 

DTC  P0141 

Rear Oxygen Sensor Heater Inoperation 

The post-catalytic heated oxygen sensor (HO2S) is used for monitoring three-way catalytic 
converter working status. The sensor compares the oxygen content in ambient air and oxygen 
content in the exhaust flow. Each heated oxygen sensor has an internal heating element for sensor 
heating. ECM controls the heated oxygen sensor heating control circuit. This makes the system 
enter into the closed-loop control mode earlier, so that ECM can calculate Air-fuel ratio earlier. 
ECM controls the heating control circuit switched on or off, so that heated type oxygen sensor 
working temperature maintains in the specified range. Engine control module detects the 
temperature by Measure the heater current. 

The rear oxygen sensor heating coil voltage is provided by The Main Relay, which is controlled by 
ECM. When the ignition switch is turned to "ON" position, the rear oxygen sensor harness 
connector EN03 terminal No.D voltage is provided by the battery. ECM controls the heater 
working hours by ECM harness connector EN01 terminal No.23. 

2.  Conditions For Setting DTC and The Fault Location: 

DTC Code 

DTC Detection 
Strategy 

Conditions For Setting The 
DTC (Control Strategy) 

Fault Locations 

P0135 

Hardware Circuit 
Inspection 

1. Engine Running Longer 

than 60 s. 

2.  At idle Running Condition. 

3. Pre-Catalytic 

Oxygen 

Sensor Heating 

4. Pre-Catalytic 

Oxygen 

Sensor Heating Control 
Terminal Disconnected. 

5.  Duration Less Than 20s. 

1. Sensor 

Circuit 

2. Sensor 

3. ECM. 

3. Circuit 

sketch 

Refer to2.12.7.24 DTC P0137 P0138 P0140. 

4. Diagnostic 

Steps: 

Note: Before carrying out this diagnosis step, observe the data list on fault diagnosis tester and 
analyze the accuracy of the data, as these will help with quick diagnosis. 

Step 1

 

Initial Inspection 

Inspect the existence of following factors that will affect the heated type oxygen sensor working 
status: 

(a)  Exhaust system leakage or blockage. 

(b)  Water enters into the heated oxygen sensor connector. 

(c)  After engine working in high temperature, whether exhaust pipes are too hot or not. 

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Step 2

 

Inspect the rear oxygen sensor heater resistance. 

(a)  Rotated ignition switch to OFF position . 

(b)  Disconnect the rear oxygen sensor wiring harness connector. 

(c)  Measure the rear oxygen sensor heater resistance. 

Standard Resistance 

Connectors C and D, 8.1-11.1 Ω @ 20°C(68 ?F) 

 

(d)  Connect the rear oxygen sensor wiring harness connector. 

Is resistance the specified value? 

 

Step 3

 

Inspect the terminal No.D to ground voltage. 

 

(a)  Rotated ignition switch to OFF 

position . 

(b) Disconnect the rear oxygen 

sensor wiring harness connector. 

(c)  Rotated ignition switch to ON 

position . 

(d) 

Measure voltage between 
Post-Catalytic oxygen sensor 
harness connector EN03 terminal 
D and ground. 

Standard Voltage: 11-14V 

(e)  Connect the rear oxygen sensor 

harness connector EN03. 

NL02-2069b

A

B

C

D

EN03 后氧传感器线束连接器

D

Is voltage the specified value? 

 

Step 4

 

Inspect the rear oxygen sensor heater control terminal continuity. 

No 

The rear oxygen sensor heater power supply circuit 
malfunction. 

Yes 

No 

Replace the rear oxygen sensor. Refer to 2.4.7.1 
Replacement of Rear Oxygen Sensor. 

Yes 

Next 

EN03 rear oxygen sensor harness connector 

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(a)  Rotated ignition switch to OFF position . 

(b)  Disconnect the rear oxygen sensor harness connector EN03. 

(c)  Disconnect ECM harness connector EN01. 

(d) Test Continuity between rear 

oxygen sensor wiring harness 
connector EN03 terminal C and 
ECM harness connector EN01 
terminal No.23. 

Standard Resistance: Less than 1 Ω 

(e)  Connect ECM harness connector 

EN01. 

(f)  Connect the rear oxygen sensor 

wiring harness connector EN03. 

NL02-2070b

A

B

C

D

EN03 后氧传感器线束连接器

C

Is resistance the specified value? 

 

Step 5

 

Inspect ECM working circuit. 

(a)  Inspect whether ECM power supply circuit is normal. 

(b)  Inspect whether ECM ground circuit is normal. 

 

(a) Replace 

ECM. 

(b)  Carry out the crankshaft position sensor learning, refer to 2.12.7.11 “Crankshaft Position 

Sensor (CKP) Learning. 

 

Step 7

 

Use fault diagnosis tester to confirm if DTC is stored again . 

(a)  Connect the fault diagnosis tester to the diagnostic interface. 

(b)  Turn ignition switch to ON position. 

Step 6

 

Replace ECM. Refer to 2.12.8.1 Replacement of Engine Control Module. 

Next 

No 

Repair the faulty part. 

Yes 

No 

ECM control circuit malfunction. 

Yes 

EN03 rear oxygen sensor harness connector 

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(c)  Clear DTC code. 

(d)  Start and run the engine at idle speed to warm up the engine for at least 5 min. 

(e)  test the vehicle on the road for at least 5min. 

(f)  Read control system DTC code again to confirm that the system has no DTC code. 

 

5. Maintenance 

guide 

: 

Refer to 2.4.6.1 “Replacement of Rear Oxygen Sensor” to replace the rear oxygen sensor. 

Step 8

 

Troubleshooting 

No 

Refer to 2.12.7.3 Intermittent Fault 
Inspection for intermittent fault. 

Yes 

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