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Home >> Mazda >> 2013 >> 5 Grand Touring >> Repair and Diagnosis >> External Pages >> Different car >> Section 57 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0301, DTC P0302, DTC P0303, DTC P0304, DTC P0305 Or DTC P0306 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Mazda MPV and 2002 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
  1. Record freeze frame data. Check for service bulletins and on-line information. Repair as necessary. After repair, go to next step.
  2. Verify Related Pending Code Or Stored DTCs -  Turn ignition off, then on (engine off). Using scan tool, verify stored DTCs. If any other DTCs are present, repair those DTC(s) first. If other DTCs are not present, go to next step.
  3. Verify Current Input Signal Status (Ignition To On /Idle) -  Access ECT, IAT, MAF, RPM, TP and VSS PIDs with ignition on and engine idling. Compare readings with specifications. See PIN VOLTAGE/PID VALUE CHARTS article. If all data is within specification, go to next step. If any data is not within specification, go to appropriate test in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. After repair, go to step  12.
  4. Verify Current Input Signal Status Under Trouble Condition -  Verify FREEZE FRAME DATA, operate vehicle under same conditions as when DTC was set. Record PID data for ECT, IAT, MAF, RPM, TP and VSS. Compare readings with specifications. See PIN VOLTAGE/PID VALUE CHARTS article. If all data is within specification, go to next step. If any data is not within specification when ignition is on and engine runs at idle, check suspected circuit or part. Refer to appropriate test in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. After repair, go to step  12.
  5. Inspect Spark Plug Condition -  Turn ignition off. Remove spark plug from suspected cylinder. If spark plug is okay, go to next step. If spark plug is wet and possibly fuel fouled, go to step  8. If plug is damaged, has excessive wear or improper gap, replace spark plug. After repair, go to step  12.
  6. Verify Ignition Coil Condition -  Check suspect ignition coil. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If ignition coil is okay, go to next step. If ignition coil is faulty, replace ignition coil. After repair, go to step  12.
  7. Inspect Fuel Injector Harness -  Remove intake air system parts to disconnect fuel injector harness connector on suspect cylinder. Connect NOID light to fuel injector harness connector terminals. If NOID light dims during cranking, go to next step. If NOID light does not operate as specified, check injector harness. Repair or replace fuel injector harness as necessary. See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. After repair, go to step  12.
  8. Inspect Fuel Injector Operation -  Remove fuel injector from suspect cylinder. Swap injector with one from another cylinder. Start engine and run at idle. If misfire DTC is not for cylinder with suspect fuel injector, go to next step. If misfire DTC is for cylinder with suspect fuel injector, replace fuel injector. After repair, go to step  12.
  9. Inspect For Air Suction At Intake Air System -  Check for air leaks around connections of dynamic chamber, intake manifold and cylinder head. If air leaks are not present, go to next step. If any leaks are present, repair or replace suspected part as necessary. After repair, go to step  12.
    WARNING: Removing radiator cap when radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury. When removing radiator cap, wrap a thick cloth around and turn it slowly.
    NOTE: Large bubbles are normal since they are remaining air coming out from engine coolant passage.
  10. Inspect Sealing Of Engine Coolant Passage -  Check cooling system for combustion gasses. Remove radiator cap. Bleed air from cooling system. Start engine and let idle. Check for small bubbles which make coolant white at filler neck. If combustion gasses are not present, go to next step. If combustion gasses are present, repair or replace faulty parts as necessary. After repair, go to step  12.
  11. Inspect Engine Compression -  Check engine compression. See MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES article. If compression is okay, go to next step. If compression is low, overhaul engine. Refer to appropriate MECHANICAL article in ENGINES. After repair, go to next step.
  12. Verify Trouble Shooting Of Misfire DTC Completed -  Reconnect all components. Start engine. Using scan tool, clear DTC. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Perform MODE 1 - PCM ADAPTIVE MEMORY PRODUCE DRIVE MODE  under DRIVE MODES. Recheck DTC. If DTCs P0301-P0306 are present, replace PCM. After repair, go to next step. If DTC is not present, go to next step.
  13. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If no other DTCs are present, testing is complete. If any other DTC is present, go to applicable test and repair.
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