2.2.7.20 DTC P0117 P0118 

1. DTC 

description: 

DTC P0117  Temperature Sensor of Engine Coolant Circuit Voltage Too Low 

 

DTC P0118 

Temperature Sensor of Engine Coolant Circuit High Voltage or Open Circuit A

ECT sensor is a variable resistor with a negative temperature coefficient and used to measure the 
temperature of engine coolant. ECM provides a 5V voltage through ECM harness connector 
EM01 terminal No.49 to ECT sensor harness connector EM23 terminal No.3 and a low internal 
reference voltage through EM01 terminal No.74 to ECT sensor connector EM23 terminal No.1. 
ECM will always record the length of time the ignition switched off. When starting, if the ignition 
switched off time reaches the pre-set time, the engine control module will compare the engine 
coolant temperature and intake air temperature in order to determine whether the difference 
between the two is in normal working range. 

2.  Conditions For Setting DTC and The Fault Location: 

DTC Code 

DTC 

Detection 

Strategy 

Conditions For Setting The DTC 
(Control Strategy) 

Fault Locations 

P0117 

1. Idle 

2. Coolant  temperature  sensor 

circuit is short to ground. 

3.  Coolant temperature by default 

changes as the running time 
changes. 

P0118 

More Than the 
Upper Limit 

Lower Than the 
Lower Limit 

1. Idle 

2. Coolant  temperature  sensor 

signal circuit is open or short to 
5V voltage. 

3.  Coolant temperature by default 

changes as the running time 
changes. 

1. Sensor 

Circuit

2. Sensor 

3. ECM. 

 

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3. Circuit 

sketch 

发

动
机

控
制

模

块

冷却液
温度传感器

74

EM01 V5RTN1

CTS

1

49

EM01

3

NL02-0036c

 

4. Diagnostic 

Steps: 

Warning! 

See Warnings Regarding Cooling System in Warnings and Cautions. 

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. 

Note: At any time do not use flammable antifreeze, such as alcohol. Combustible antifreeze can 
cause serious fires. 

Step 1 

Initial Inspection 

(a)  Inspect the temperature sensor of engine coolant for whether there is evidence of corrosion, 

as well as the engine coolant is leaking through the sensor. 

(b)  Inspect whether the engine coolant level in the reservoir of cooling system is correct. 

 

Step 2 

Measure resistance of temperature sensor of engine coolant. 

 

Next 

Coolanttemperature 
sensor 

Engi

ne

 co

ntr

ol mo

dul

e 

180

(a)  Rotated ignition switch to OFF 

position . 

(b) 

Disconnect the temperature 
sensor of engine coolant harness 
connector EM23. 

(c) Measure the resistance of 

temperature sensor of engine 
coolant. 

冷却液温度传感器线束连接器

EM23

1

2

3

NL02-0037c

Standard resistance value (for detailed parameters, see 2.2.1.2 Temperature-resistance 
Relationship of Temperature Sensor): 20 (68

℃

°F) 3511±2.6%Ω 

(d)  Connect the temperature sensor of engine coolant harness connector EM23. 

Is resistance the specified value? 

 

Step 3 

Measure temperature sensor of engine coolant signal circuit. 

(a)  Rotated ignition switch to OFF position . 

(b)  Disconnect the temperature sensor of engine coolant harness connector EM23. 

(c)  Rotated ignition switch to ON position . 

(d)  Measure voltage between temperature sensor of engine coolant EM23 terminal No.3 and a 

reliable ground. 

Standard Voltage: 4.7-5.5V 

(e)  Connect the temperature sensor of engine coolant harness connector EM23. 

Is the voltage normal? 

 

Step 4 

Measure ground circuit of temperature sensor of engine coolant. 

(a)  Rotated ignition switch to OFF position . 

(b)  Disconnect the temperature sensor of engine coolant harness connector EM23. 

(c)  Rotated ignition switch to ON position . 

(d)  Measure resistance between temperature sensor of engine coolant harness connector EM23 

terminal No.1 and reliable ground. 

Standard Resistance: Less than 3 Ω 

No 

Go to step 5 

Yes 

No 

Replace the temperature sensor of engine 
coolant, go to step 9. 

Yes 

Coolanttemperature sensorharness 

connectorEM23 

181

(e)  Connect the temperature sensor of engine coolant harness connector EM23. 

Is the resistance normal? 

 

Step 5 

Inspect the temperature sensor of engine coolant signal circuit. 

 

(a)  Rotated ignition switch to OFF 

position . 

(b) 

Disconnect the temperature 
sensor of engine coolant harness 
connector EM23. 

(c) 

Disconnect ECM harness 
connector EM01. 

(d) Measure  resistance  between 

engine coolant temperature 
sensor wire harness connector 
EM23 terminal 3 and ECM wire 
harness connector terminal 49. 
Inspect whether there is 
short-circuit situation. 

ECM线束连接器

EM01

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

GC02-1004c

(e)  Measure resistance between engine coolant temperature sensor wire harness connector EM23 

terminal 3 and reliable grounding. Inspect whether there is grounding short-circuit. 

(f)  Measure voltage between temperature sensor of engine coolant wiring harness connector 

EM23 terminal No.3 and a reliable ground. Inspect whether the circuit is short to power 
supply. 

Test Items 

Standard Value 

Resistance Between EM23 (3) and EM01 (49) 

Less than 1 Ω 

Resistance Between EM23 (3) and a Reliable Ground 

10 kΩ or higher 

Voltage Between EM23 (3) and a Reliable Ground 

0V 

 

Step 6 

Inspect the temperature sensor of engine coolant ground circuit. 

(a)  Rotated ignition switch to OFF position . 

(b)  Disconnect the temperature sensor of engine coolant harness connector EM23. 

(c)  Disconnect ECM harness connector EM01. 

(d)  Measure resistance between engine cooling temperature sensor wire harness connector EM23 

terminal 1 and ECM wire harness connector terminal 74. Inspect whether there is 
short-circuit situation, if yes, repair fault position. 

(e)  Measure voltage between temperature sensor of engine coolant harness connector EM23 

No 

Go to step 6 

Yes 

Go to step 7 

Next 

Go to step 7 

ECMharness connectorEM01 

182