LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2010 >> 3 Mazdaspeed, 2.3 4 >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System L3 With TC] (3 Of 5) >> DTC P0300:00 >> Notes
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

DTC P0300:00: Notes

DTC P0300:00 (L3 WITH TC) DETECTION CONDITION & POSSIBLE CAUSES

DTC P0300:00 Random misfire detected
DETECTION CONDITION 
  • The PCM monitors the CKP sensor input signal interval time. The PCM calculates the change of interval time for each cylinder. If the change of interval time exceeds the preprogrammed criteria, the PCM detects a misfire in the corresponding cylinder. While the engine is running, the PCM counts the number of misfires that occurred at 200 crankshaft revolutions and 1, 000 crankshaft revolutions  and calculates a misfire ratio for each crankshaft revolution. If the ratio exceeds the preprogrammed criteria, the PCM determines that a misfire, which can damage the catalytic converter or affect emission performance, has occurred.

Diagnostic support note 
  • This is a continuous monitor (misfire).
  • The MIL illuminates if the PCM detects a misfire which affects emission performance in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
  • The MIL flashes if the PCM detects a misfire which can damage the catalytic converter during the first drive cycle.
  • PENDING CODE is available if the PCM detects a misfire which affects emission performance during the first drive cycle.
  • FREEZE FRAME DATA (Mode 2)/Snapshot data is available.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • Erratic signal to PCM
    • APP sensor signal malfunction
    • ECT sensor No. 1 signal malfunction
    • IAT sensor signal malfunction
    • MAF sensor signal malfunction
    • CKP sensor signal malfunction
    • TP sensor signal malfunction
    • VSS signal malfunction
    • Related connector or terminals malfunction
    • Related wiring harness malfunction
  • CMP sensor malfunction
  • CKP sensor looseness
  • Ignition coil related wiring harness malfunction
  • Ignition system malfunction
    • Spark plug malfunction
    • Ignition coil malfunction
  • Air restriction or leakage in intake air system (between MAF sensor and intake manifold)
  • MAF sensor contamination
  • Turbocharger malfunction (turbine wheel/compressor wheel damaged, stuck)
  • Low-pressure side fuel delivery system malfunction
    • Fuel pump unit malfunction
    • Fuel pressure regulator (built-in fuel pump unit) malfunction
    • Fuel line clogged
    • Fuel filter clogged
    • Fuel leakage in fuel line
    • Fuel runout
  • Improper operation of variable valve timing control system
  • Purge solenoid valve malfunction
  • Vacuum hoses damage or improper connection
  • Improper operation of fuel pump speed control
  • Engine internal malfunction
    • Engine coolant leakage into combustion chamber
    • Insufficient engine compression

    High-pressure side fuel delivery system malfunction

    • Fuel pressure sensor (built-in fuel delivery pipe) malfunction
    • Relief valve (built-in fuel delivery pipe) malfunction
    • High pressure fuel pump malfunction
    • Spill valve control solenoid valve (built-in high pressure fuel pump) malfunction
  • EGR valve malfunction
  • PCV valve malfunction
  • Poor quality fuel
  • PCM malfunction