(c)

Clear DTC code.

(d)

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

(e)

Road test the vehicle for at least 5 min.

(f)

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

Next

Step 6

Diagnostic completed.

2.2.7.15 DTC P0030 P0031 P0032 P0053

1. DTC Descriptor:

DTC

P0030

Pre-Catalytic oxygen sensor heating control circuit open

DTC

P0031

Pre-Catalytic oxygen sensor heating control circuit short to ground

DTC

P0032

Pre-Catalytic oxygen sensor heating control circuit short to power supply

The Pre-Catalytic heated oxygen sensor (HO

2

S) is used for fuel control. The sensor compares the oxygen content in ambient air

with the oxygen content in 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 commands heater control module switched on or off, so that heated oxygen
sensor works within the specified working temperature range. Engine control module detects the temperature by Measure the heater
current.

The Pre-Catalytic heated 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.1 voltage is provided by the battery. ECM controls
heater working time through ECM harness connector EN01 terminal No.6.

2. Conditions For Setting DTC and The Fault Location:

DTC Code

DTC Detection Strategy

Conditions For Setting The DTC (Control

Strategy)

Fault Locations

P0030
P0031
P0032

Hardware Circuit Checks

1. Circuit Open.

2. Circuit Short to Ground.

3. Circuit Short to Power Supply.

1. Sensor Circuit

2. Sensor

3. ECM

P0053

Resistance is greater than the
set value.

1. The current Pre-Catalytic oxygen sensor

internal resistance is greater than 1500 Ω.

2. The current exhaust gas temperature is

between 200°C (392 ºF) and 550°C
(1,022 ºF).

Engine

Control System JL4G18-D

2-79

3. Schematic:

12

13

From Battery

Main Relay

Pre-catalytic Oxygen Sensor

To Post-catalytic Oxygen Sensor

Engine 

Control 

Module

FE02-5008b

4. Diagnostic Steps:

Note

Before carrying out this diagnosis step, observe the data list on scan tool and analyze the accuracy of the data, as
these will help with quick diagnosis.

Step 1

Initial inspection.

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

(a)

Exhaust system leaks or blockage.

(b)

Water entering into the heated oxygen sensor connector.

(c)

After engine working in high temperatures, whether exhaust
pipes are too hot.

Next

Step 2

Check the Pre-Catalytic oxygen sensor heater resistance.

2-80

Control System JL4G18-D

Engine

Pre-catalytic Oxygen Sensor

FE02-5009b

(a)

Turn the ignition switch to "OFF" position.

(b)

Disconnect oxygen sensor wiring harness connector.

(c)

Measure heater resistance between the Pre-Catalytic
oxygen sensor terminal No.1 and terminal No.2.

Standard Resistance: 9 Ω(68 ºF) at 20°C

(d)

Connect the Pre-Catalytic oxygen sensor wiring harness
connector.

Is resistance the specified value?

No

Replace the Pre-Catalytic oxygen sensor.
Refer to 

2.4.7.2

 

Pre-Catalytic Oxygen Sensor

Replacement

Yes

Step 3

Check the terminal No.2 to ground voltage.

FE02-5010b

1

2

3

4

Pre-catalytic Oxygen Sensor Harness Connector 

EN02

(a)

Turn the ignition switch to "OFF" position.

(b)

Disconnect the Pre-Catalytic oxygen sensor wiring harness
connector.

(c)

Turn the ignition switch to "ON" position.

(d)

Measure the Pre-Catalytic oxygen sensor wiring harness
connector EN02 terminal No.1 to ground voltage.

Standard Voltage Value: Voltage between the EN02 terminal No.1
and the ground is 11-14 V.

(e)

Connect the Pre-Catalytic oxygen sensor wiring harness
connector.

Is voltage the specified values?

No

Pre-Catalytic Oxygen Sensor Power Supply
Circuit Fault

Yes

Step 4

Check the Pre-Catalytic oxygen sensor terminal heating control signal continuity.

Engine

Control System JL4G18-D

2-81

FE02-5011b

1

3

5

7

8

6

4

2

9

10

11

12

13

23

24

25

26

27

28

29

30

37

51

52

53

54

55

56

57

58

59

60

61

62

63

64

38

39

40

41

42

43

44

45

46

47

48

49

50

31

32

33

34

35

36

14

15

16

17

18

19

20

21

22

1

2

3

4

Pre-catalytic Oxygen Sensor Harness 

Connector EN02

ECM Harness Connector EN01

(a)

Turn the ignition switch to "OFF" position.

(b)

Disconnect the Pre-Catalytic oxygen sensor wiring harness
connector EN02.

(c)

Disconnect ECM harness connector EN01.

(d)

Test continuity between the Pre-Catalytic oxygen sensor
wiring harness connector EN02 terminal No.2 and ECM
harness connector EN01 terminal No.6.

Standard Resistance: Less than 1 Ω

(e)

Connect ECM harness connector EN01.

(f)

Connect the Pre-Catalytic oxygen sensor wiring harness
connector EN02.

Is resistance the specified value?

No

ECM control circuit malfunction

Yes

Step 5

Check ECM working circuit.

(a)

Check whether ECM power supply circuit is normal.

(b)

Check whether ECM ground circuits is normal.

No

Repair the faulty part.

Yes

Step 6

Replace ECM. Refer to 

2.2.8.8

 

Engine Control Module Replacement

.

Next

Step 7

Use scan tool to confirm whether the DTC code is stored again.

(a)

Connect scan tool to the datalink connector.

(b)

Turn the 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)

Road test the vehicle for at least 5 min.

(f)

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

No

Intermittent Fault. Refer to 

2.2.7.3

 

Intermittent

Fault Check

2-82

Control System JL4G18-D

Engine