(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 10 min. 

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

 

5. Maintenance 

guide: 

Refer to 2.12.8.5 “Replacement of Fuel Injectors” to replace the fuel injectors. 

Step 10 

Troubleshooting 

No 

Refer to 2.12.7.3 Intermittent Fault 
Inspection for intermittent fault. 

Yes 

815

2.12.7.33 DTC P0300   

1. DTC 

description: 

DTC  P0300 

Multi-Cylinder Misfire 

The engine control module (ECM) uses information from the crankshaft position (CKP) sensor 
and the camshaft position (CMP) sensors to determine when an engine mis?re is occurring. By 
monitoring variations in the crankshaft rotation speed for each cylinder ECM is able to detect 
individual mis?re events. When a misfire happens, unburnt mixture will be discharged into the 
exhaust system and burnt in the 3-way catalytic converter (TWC) which will overheat the 
converter. A misfire rate that is high enough can cause 3-way catalytic converter damage. The 
malfunction indicator lamp (MIL) will ash ON and OFF when the conditions for catalytic 
converter overheated are present. A DTC will be set. 

2.  Setting DTC code and Fault Location: 

DTC Code 

DTC Detection 
Strategy 

Conditions For Setting The 
DTC (Control Strategy) 

Fault Locations 

P0300 

Under stable 
operating 
conditions, ECM 
detects the 
crankshaft 
rotation speed 
fluctuations. 

Under stable operating 
conditions, When the ECM 
detects the crankshaft rotation 
speed fluctuations exceeding the 
threshold set by the system: 
When the fire degree is too low 
for affecting the exhaust 
emission, without emergency 
control scheme, only record the 
fault code and freeze the data 
stream as well as turn on the 
fault indication. 

Lamp; when the fire degree is 
too high, which may lead to 
overheating of the catalyst, 
compel to entering the fuel 
open-loop control working 
condition, and inhibit oxygen 
correction learning. The fault 
indicator lamp flickers with the 
frequency of 1HZ. 

1. Connector Loose or 

Poor Connection 

2.  Vacuum Tube Hose 

Broken or Loose 

3. Ignition 

System 

4. Fuel 

Injectors 

5. Fuel 

Pressure 

6.  Intake Air Pressure 

Sensor 

7. Engine 

Coolant 

Temperature Sensor 

8. Cylinder 

Compression 

Pressure 

9.  Valve Clearance and 

Timing 

10. Evaporative Emission 

Control System 

11. Purged 

Crankcase 

Ventilation System 

12. Intake System 

13.  Poor Exhaust System 

Ventilation 

14. ECM. 

816

3. Circuit 

sketch 

Ignition System 

NL02-2098b

ECM

44

EN01

BAT

20A

E

F

22

MPR

86

87

30

85

发动机主继电器

4

EN01

1

EN01

A EN20

B EN20

C EN20

点火线圈

COILA

COILB

 

Fuel Injector Nozzle 

NL02-2099b

6

EN01

A

EN11

B

EN11

1缸燃油喷射器

ECM

INJA

8

EN01

A

EN12

B

EN12

2缸燃油喷射器

INJD

7

EN01

A

EN13

B

EN13

3缸燃油喷射器

INJB

25

EN01

A

EN14

B

EN14

4缸燃油喷射器

INJC

44

EN01

BAT

15

A

E

F2

1

MPR

86

87

30

85

发动机主继电器

 

2. Diagnostic 

Steps: 

Notes: 

–  If the control system stores DTC other than misfire, diagnose these DTC first and 

eliminate the faults. 

Engine Main 
relay 

Ignition coil

Engine main 
relay 

1st cylinderfuel injector

2nd cylinderfuel injector

3rd cylinderfuel injector

4th cylinderfuel injector

817

– 

If the vehicle does not have a misfire when sent to a service station, road test the vehicle, so 
that the misfire will occur again. Use fault diagnosis tester to record ECM data when 
misfire is occurring, in order to facilitate analyzing the cause of the fault. 

– 

If after a long period road test, ECM does not store any misfire associated DTC codes, then 
the fault may be due to the following reasons: 

• 

Overfill fuel tank and fuel enters the evaporative emission control system, so that the 
mixture is too thick and causes misfire. 

• 

Use improper fuel caused poor combustion and misfire. 

• 

Contaminated spark plug causes the ignition failure and misfire. 

• 

Carry out basic inspections at fault locations identified by DTC codes. 

– 

Road test the vehicle after repair to confirm no DTC is stored. 

Step 1

 

Initial Inspection 

(a)  Inspect the harness connector for damage, poor connection, aging or signs of loosening. 

(b)  Inspect the vacuum tube for damaged, loose, leakage and so on. 

 

Step 2

 

Inspect other 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 

GO to Step 

DTC codes other than P0300 

No 

DTCP0300 Yes 

 

Step 3

 

Inspect the vacuum tube and the air intake system. 

(a)  Inspect vacuum canister solenoid valve connection is correct or not and leakage. 

(b)  Inspect the vacuum brake booster vacuum tube connection is correct or not and leakage. 

(c)  Inspect the intake tube pressure sensor connection is correct or not and leakage. 

No 

Refer to 2.12.7.14 DTC Chapter Index. 

Yes 

Next 

818