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HOMESERVICE MANUALSMAZDA20105 SPORT, 2.3 L, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 431 (ON-BOARD DIAGNOSTIC (ENGINE CONTROL SYSTEM 13BMSP])DTC P0300DIAGNOSTIC PROCEDURE
2010 Mazda 5 Sport, 2.3 L, Standard

Diagnostic procedure

2010 Mazda 5 Sport, 2.3 L, StandardSECTION Diagnostic procedure
WARNING: This page is about a different car, the 2005 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0300 DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (Misfire related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
 Yes Perform repair or diagnosis according to the available repair information.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 VERIFY RELATED PENDING CODE OR STORED DTC 
  • Turn the ignition switch off, then to the ON position (Engine off).
  • Verify the related PENDING CODE or stored DTCs.
  • Are other DTCs present?
 Yes Go to the appropriate DTC inspection.
(See DTC TABLE .)
No Go to the next step.
4 VERIFY CURRENT INPUT SIGNAL STATUS 
  • Connect the WDS or equivalent to the DLC-2.
  • Verify the following PIDs.

    (See PCM INSPECTION .)

    • APP
    • ECT
    • MAF
    • TP
    • VSS
  • Are the PIDs normal?
 Yes Go to the next step.
No Inspect the malfunctioning part according to the inspection results.
Then go to Step 22.
5 VERIFY CURRENT INPUT SIGNAL STATUS UNDER FREEZE FRAME DATA CONDITION 
  • Connect the WDS or equivalent to the DLC-2.
  • Verify the following PIDs under the FREEZE FRAME DATA condition.

    (See PCM INSPECTION .)

    • APP
    • ECT
    • MAF
    • TP
    • VSS
  • Are the PIDs normal?
 Yes Go to the next step.
No Inspect the malfunctioning part according to the inspection results.
Then go to Step 22.
6 INSPECT ECCENTRIC SHAFT POSITION SENSOR  Yes Replace the eccentric shaft position sensor, then go to Step 22.
(See ECCENTRIC SHAFT POSITION SENSOR REMOVAL/INSTALLATION .)
No Go to the next step.
7 INSPECT IGNITION COIL OPERATION AND HIGH-TENSION LEAD WITH TIMING LIGHT 
  • Inspect the blinking condition on each high-tension leads using timing light at idle.
  • Do all the high-tension leads show blinking condition?
 Yes Go to Step 11.
No Go to the next step.
8 INSPECT HIGH-TENSION LEAD OF NO BLINKING HIGH-TENSION LEAD  Yes Replace the malfunctioning high-tension lead, then go to Step 22.
(See HIGH-TENSION LEAD REMOVAL/INSTALLATION .)
No Go to the next step.
9 INSPECT IGNITION COIL POWER CIRCUIT FOR OPEN CIRCUIT OR SHORT TO GROUND 
  • Turn the ignition switch to the ON position (Engine off).
  • Measure the voltage between ignition coil terminal C (wiring harness-side) and body ground.
  • Is the voltage B+  ?
 Yes Go to the next step.
No Repair or replace the wiring harness for a possible open circuit or short to ground, then go to Step 22.
10 INSPECT IGNITION COIL  Yes Replace the ignition coil, then go to Step 22.
(See IGNITION COIL REMOVAL/INSTALLATION .)
No Inspect the spark plug.
(See SPARK PLUG INSPECTION .)
If the spark plug is normal, go to the next step.
11 VERIFY CURRENT INPUT SIGNAL STATUS OF MAF SENSOR 
  • Connect the WDS or equivalent to the DLC-2.
  • Start the engine.
  • Access the MAF PID.
  • Verify that the MAF PID changes quickly according to the RPM when the engine is raced.
  • Is the PID normal?
 Yes Go to the next step.
No Replace the MAF/IAT sensor, then go to Step 22.
(See MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION .)
12 INSPECT INTAKE-AIR SYSTEM FOR EXCESSIVE AIR SUCTION 
  • Visually inspect for looseness, cracks or damaged hoses in intake-air system.
  • Is there any malfunction?
 Yes Repair or replace the malfunctioning part, then go to Step 22.
No Go to the next step.
13 INSPECT FUEL LINE PRESSURE  Yes
  • If the fuel line pressure is too low, go to the next step.
  • If the fuel line pressure is too high, replace the fuel pump unit, then go to Step 22.

    (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
No Go to Step 15.
14 INSPECT FUEL SYSTEM FOR FUEL LEAKAGE 
  • Visually inspect fuel leakage in the fuel system.
  • Is there fuel leakage?
 Yes Repair or replace the malfunctioning part, then go to Step 22.
No Replace the fuel pump unit, then go to Step 22.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
15 INSPECT ENGINE COMPRESSION  Yes Go to the next step.
No Go to Step 20.
16 INSPECT METERING OIL PUMP  Yes Repair or replace the malfunctioning part according to the inspection results.
Overhaul or replace the engine.
Then go to Step 22.
No Go to the next step.
17 INSPECT ENGINE OIL CONDITION 
  • Inspect the engine oil condition.
  • Is the engine oil condition normal?
 Yes Go to the next step.
No Replace the engine oil.
Inspect the ECT sensor and related harnesses.
(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION .)
Overhaul or replace the engine.
Then go to Step 22.
18 INSPECT OIL PRESSURE  Yes Repair or replace the malfunctioning part according to the inspection results.
Overhaul or replace the engine.
Then go to Step 22.
No Go to the next step.
19 INSPECT OIL PASSAGE 
  • Inspect the oil pipe between metering oil pump and metering oil nozzle.
  • Is there any malfunction?
 Yes Inspect and repair for leakage or clogging in the engine oil passage.
Overhaul or replace the engine.
Then go to Step 22.
No Overhaul or replace the engine.
Then go to Step 22.
20 INSPECT PURGE CONTROL SYSTEM OPERATION  Yes Repair or replace the malfunctioning part according to the inspection results.
Then go to Step 22.
No Go to the next step.
21 INSPECT ENGINE COOLANT PASSAGE FOR ENGINE COOLANT LEAKAGE  Yes Repair or replace the malfunctioning part according to the inspection results.
Then go to the next step.
No Go to the next step.
22 VERIFY TROUBLESHOOTING OF DTC P0300 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the WDS or equivalent.
  • Start the engine and warm it up completely.
  • Is the PENDING CODE same as the DTC present?
 Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION .)
No Go to the next step.
23 VERIFY AFTER REPAIR PROCEDURE  Yes Go to the applicable DTC inspection.
(See DTC TABLE .)
No DTC troubleshooting completed.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.