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Home >> Mazda >> 2017 >> CX-5 Grand Select, AWD >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic - Engine Control System (1 Of 5) >> DTC P0300-00: Random Misfire Detected >> Troubleshooting Diagnostic Procedure >> Intention of troubleshooting procedure
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Intention of troubleshooting procedure

STEP INSPECTION RESULTS ACTION
1 PURPOSE: DETERMINE INTEGRITY OF SPARK PLUG Yes Replace the spark plug, then go to Step 10.
(See SPARK PLUG REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Go to the next step.
2 PURPOSE: DETERMINE INTEGRITY OF IGNITION COIL Yes Replace the ignition coil/ion sensor, then go to Step 10.
(See IGNITION COIL/ION SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Go to the next step.
3 PURPOSE: DETERMINE INTEGRITY OF FUEL INJECTOR Yes Replace the fuel injector, then go to Step 10.
(See FUEL INJECTOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Go to the next step.
4 PURPOSE: VERIFY IF MALFUNCTION RELATED TO INTAKE-AIR SYSTEM IS CAUSE OF MISFIRE
  • Visually inspect for loose, cracked or damaged hoses on intake air system.
  • Is there any malfunction?
Yes Repair or replace the malfunctioning part according to the inspection results, then go to Step 10.
No Go to the next step.
5 PURPOSE: VERIFY IF POOR DRIVE BELT ASSEMBLY IS CAUSE OF MISFIRE Yes Assemble drive belt correctly, then go to Step 10.
(See DRIVE BELT REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Go to the next step.
6 PURPOSE: VERIFY IF FOREIGN MATTER ON DRIVE BELT IS CAUSE OF MISFIRE
  • Verify if oil is on the drive belt.
  • Is there foreign matter on the drive belt?
Yes Remove the foreign matter on the drive belt, then go to Step 10.
No Go to the next step.
7 PURPOSE: DETERMINE INTEGRITY OF DRIVE BELT AUTO TENSIONER Yes Replace the drive belt auto tensioner, then go to Step 10.
(See DRIVE BELT AUTO TENSIONER REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Go to the next step.
8 PURPOSE: VERIFY IF MALFUNCTION RELATED TO ENGINE COMPRESSION IS CAUSE OF MISFIRE Yes Go to the next step.
No Replace or overhaul the engine, then go to Step 10.
9 PURPOSE: VERIFY IF MALFUNCTION RELATED TO SEALING OF ENGINE UNIT (COMBUSTION CHAMBER AND ENGINE COOLANT PASSAGE) IS CAUSE OF MISFIRE Yes Engine coolant leakage from the engine (between the combustion chamber and the engine coolant passage) may have occurred.
  • Verify the conditions of the gasket and the cylinder head.
  • If there is any malfunction:
  • Repair or replace the malfunctioning part according to the inspection results, then go to the next step.
No Go to the next step.
10 PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION Yes Repeat the inspection from Step 1.
Go to the next step.
No Go to the next step.
11 PURPOSE: VERIFY IF THERE IS ANY OTHER MALFUNCTION
  • Is any other DTC or pending code stored?
Yes Go to the applicable DTC inspection.
(See DTC TABLE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .)
No DTC troubleshooting completed.