Geely Emgrand X7. Manual part — 192

2.12.7.23 DTC P0135

1. DTC

description:

DTC P0135

Front oxygen sensor heater fails

The pre-catalytic heated oxygen sensor (HO2S) is used for fuel control. 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 front 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, harness connector EN02 terminal
No.D voltage is provided by the battery. ECM controls heater working hours through ECM
harness connector EN01 terminal No.14.

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 to 2.12.7.22 DTC P0131 P0132 P0133 P0134.

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.

767

Step 2

Inspect front oxygen sensor heater resistance.

(a) Rotated ignition switch to OFF

position .

(b) Disconnect front oxygen sensor

wiring harness connector.

(c) Measure heater resistance

between front oxygen sensor
terminals C and D.

Standard Resistance

20 (68ºF) 8.1

℃

-11.1Ω

(d) Connect front oxygen sensor

wiring harness connector.

Is resistance the specified value?

NL02-2062b

A

B

C

D

EN02 前氧传感器线束连接器

D

Step 3

Inspect the terminal No.D to ground voltage.

(a) Rotated ignition switch to OFF

position .

(b) Disconnect front oxygen sensor

wiring harness connector.

(c) Rotated ignition switch to ON

position .

(d) Measure the front oxygen sensor

harness connector EN02 terminal
No.D to ground voltage.

Standard Voltage: 11-14V

(e) Connect the front oxygen sensor

harness connector EN02.

NL02-2063b

A

B

C

D

EN02 前氧传感器线束连接器

C

Is voltage the specified value?

No

Front oxygen sensor heater power supply
circuit fault

Yes

No

Replace the front oxygen sensor. Go to
step 11.

Yes

Next

EN02Front oxygen sensor harness

connector

EN02Front oxygen sensor harness

connector

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Step 4

Inspect the front oxygen sensor terminal heating control signal continuity.

(a) Rotated ignition switch to OFF position .

(b) Disconnect the front oxygen sensor harness connector EN02.

(c)

Disconnect ECM harness
connector EN01.

(d) Test Continuity between front

oxygen sensor wiring harness
connector EN02 terminal C and
ECM harness connector EM01
terminal No.24.

Standard Resistance: Less than 1 Ω

(e) Connect ECM harness connector

EN01.

(f) Connect the front oxygen sensor

harness connector EN02.

NL02-2064b

EN01 发动机控制模块线束连接器

1

2

4

5

3

81

63

44

25

6

62

43

24 23 22 21 20 19 18 17 16 15 14 13 12 11 10

9

8

7

26

42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27

45

46

61 60 59 58

57 56 55

54 53 52 51 50 49 48 47

64

65

66

80 79 78 77 76 75 74 73 72 71 70 69 68 67

24

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.

Step 6

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

(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 .

Yes

No

Repair the faulty part.

Yes

No

ECM control circuit malfunction

Yes

EN01Engine control module harness

connector

769

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

(b) Turn ignition switch to ON position.

(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.

Step 8

Troubleshooting

5. Maintenance

guide:

Refer to 2.4.6.2 “Replacement of Front Oxygen Sensor” to replace the front oxygen sensor

No

Refer to 2.2.7.3 Intermittent Fault
Inspection for intermittent fault.

Yes

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