2.12.7.22 DTC P0131 P0132 P0133 P0134 

1. DTC 

description: 

DTC  P0131 

Front Oxygen Sensor Circuit Short to Low Voltage 

 

DTC  P0132 

Front Oxygen Sensor Circuit Short to High Voltage 

 

DTC  P0133 

Slow response of front oxygen sensor 

 

DTC  P0134 

Front Oxygen sensor is open 

After the vehicle started, ECM works in open-loop mode, in which ECM ignores the front oxygen 
sensor signal voltage when calculating the Air-Fuel ratio. The control module provides 
approximately 450mV reference voltage to the front oxygen sensor. When the engine starts 
running, the front oxygen sensor will be heated and begin to generate a 0-0.1 V voltage. This 
voltage fluctuates. Once ECM detects that the front oxygen sensor voltage exceeds a preset 
threshold voltage, ECM immediately enters into the closed-loop mode. Control module 
determines the Air-fuel ratio using the received front oxygen sensor voltage signal. If the front 
oxygen sensor voltage increases to over the reference voltage (tend to 1 V), it indicates that the air 
fuel mixture is too rich. If the front oxygen sensor's voltage decreased to below the reference 
voltage (tend to 0 mV), the mixture is too thin. 

ECM provides a signal through ECM harness connector EN01 terminal No.10 to front oxygen 
sensor harness connector EN02 terminal B and an internal low reference voltage through ECM 
harness connector EN01 terminal No.2 to front oxygen sensor wiring harness connector EM02 
terminal No. A. 

2.  Conditions For Setting DTC and The Fault Location: 

DTC 
Code 

DTC Detection Strategy

Conditions For Setting The 
DTC (Control Strategy) 

Fault Locations 

P0131 

1. Engine Running Longer 

than 60s. 

2.  Water temperature is more 

than 70 (158 ºF)

℃

 

3. Short circuit of front 

oxygen sensor to 
grounding. 

4.  Duration Longer Than 13s.

P0132 

1. Front 

Oxygen 

Sensor Voltage Too 
High 

2. Pre-Catalytic 

Oxygen Sensor 
Voltage Too Low 

1. Engine Running Longer 

than 60s. 

2.  Water temperature is more 

1. Sensor 

Circuit 

2. Sensor 

3. ECM. 

759

than 70 (158 ºF)

℃

 

3. Shortly connect front 

oxygen sensor signal and 
power supply. 

4.  Duration Longer Than 13s.

P0133 

The time for the variation 
of the oxygen sensor 
against the oxygen 
concentration in the 
exhaust emissions 
exceeds the upper limit. 

The time for the variation 
of the oxygen sensor 
against the oxygen 
concentration in the 
exhaust emissions 
exceeds the lower limit. 

1. Engine Running Longer 

than 60s. 

2.  Water temperature is more 

than 70 (158 ºF)

℃

 

3.  Engine speed range is 

1,700-2,300 rpm. 

4.  Oxygen sensors to the 

exhaust oxygen 
concentration changes 
responding time longer 
than the system preset 
threshold. 

1. Sensor 

Circuit 

2. Sensor 

3. ECM 

4.Mixture is too 

thick 

5.Mixture Too Lean 

P0134 

1. Signal Circuit Open. 

2.Oxygen Sensors High- 
Temperature and High 
Resistance. 

1. Engine Running Longer 

than 60s. 

2.  Water temperature is more 

than 70 (158 ºF)

℃

 

3.  Duration Longer Than 80s.

1. Sensor 

Circuit 

2. Sensor 

3. ECM 

3. Circuit 

sketch 

NL02-2057b

BAT

15

A

E

F2

1

86

87

30

85

发动机主继电器

D

EN02

C

EN02

B

EN02

A

EN02

前氧传感器

24

EN01 O

2

AHTR

47

EN01 O

2

HI

73

EN01

44

EN01

V5RTN3

MPR

ECM

 

Engine 
main relay 

Front oxygen sensor

760

4. Diagnostic 

Steps: 

Step 1

 

Connect a fault diagnosis tester. 

 

Step 2

 

Start engine and turn on the fault diagnosis tester. 

 

Step 3

 

(c)  Keep the engine speed at 2,500 rpm for more than 2 min to warm up the engine, 
until the engine coolant temperature reaches 80°C (176ºF) 

 

Step 4

 

Select on the fault diagnosis tester: Engine / Read Data Flow / Group 1 Oxygen Sensor 
Voltage 1 (front oxygen sensor). 

 

Step 5

 

Observe the pre-catalytic oxygen sensor output voltage. The data stream 
should fluctuate within 0.1-0.8 V.

 

 

Step 6

 

Test the oxygen sensor signal. 

(a)  If the voltage data is consistently lower than 0.45 V (mixture too thin), carry out the 

following inspection steps: 

• 

Spray proper amount of propane gas into the intake. 

• 

Inspect whether the front oxygen sensor voltage data has a significant change, in which case 
the signal voltage will increase rapidly. 

(b)  If the voltage data is consistently higher than 0.45V (mixture too thick), carry out the 

following inspection steps: 

• 

Put the gear into neutral. 

• 

Apply hand brake. 

• 

Press the accelerator pedal so the engine speed suddenly increases to 4,000 rpm and then 
quickly release the accelerator pedal. 

• 

Repeat the previous step more than 3 times. 

• 

Observe whether there is a significant change in the front oxygen sensor voltage data, as the 
signal voltage will decrease rapidly. 

Yes 

Refer to 2.2.7.3 Intermittent Fault 
Inspection for intermittent fault. 

No 

Next 

Next 

Next 

Next 

761

During the above test, the oxygen sensor signal voltage should have a significant change. 

Is voltage changed significantly? 

 

Step 6

 

Inspect there are no other control system DTC codes output. 

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

(b)  Turn ignition switch to ON position. 

(c)  Press the fault diagnosis tester power button. 

(d)  Select the following menu items: Engine/Read DTC codes. 

(e)  Read DTC codes. 

Results 

DTC Codes Shown 

To Step 

DTC    was except for P0131、P0133、P0134 No 

P0131、P0133、P0134 Yes 

 

Step 8

 

Measure Pre-Sensor Signal Circuit 

 

(a)  Rotated ignition switch to OFF 

position . 

(b) Disconnect the front oxygen 

sensor harness connector EN02. 

(c)  Rotated ignition switch to ON 

position . 

(d) Measure the voltage value 

between the front oxygen sensor 
wiring harness connector EN02 
terminal No.B and reliable 
ground. 

Standard Voltage: 0.35-0.5V 

(e)  Connect the front oxygen sensor 

harness connector EN02. 

NL02-2058b

A

B

C

D

EN02 前氧传感器线束连接器

B

No 

Refer to 2.12.7.14 DTC Chapter Index. 

Yes 

Yes 

Inspect the cause for engine 
air-fuel ratio too lean/too rich. 
Refer to 2.12.7.4 Fault Symptom 
Table. 

No 

EN02 front oxygen sensor harness 

connector 

762