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DTC P0300: Random Misfire Detected

NOTE: For terminal identification, see TERMINAL IDENTIFICATION . For circuit and wire color identification, see WIRING DIAGRAMS article.
  1. Using scan tool, check Crankshaft Position (CKP) sensor pulse width (item 22) while maintaining a constant RPM. If pulse width is constant, go to next step. If pulse width is not constant, go to step 5).
  2. Check wiring harness between CKP sensor and PCM. Repair wiring harness as necessary. Go to step 12). If wiring harness is okay, go to next step.
  3. Check CKP sensor and PCM connectors for damage. Repair or replace connectors as necessary. Go to step 12). If connectors are okay, go to next step.
  4. Ensure CKP sensor and sensing plate are properly installed. Correct installation as necessary. Go to step 12). If CKP sensor and sensing plate are installed properly, replace CKP sensor. Go to step 12).
  5. Ensure engine coolant temperature is at 68°F (20°C). Disconnect each fuel injector connector. Using DVOM, check resistance across fuel injector terminals. If resistance is not 13-16 ohms replace fuel injector(s). Go to step 12). If resistance is as specified, go to next step.
  6. Inspect wiring harness between each fuel injector and PCM. Repair wiring harness as necessary. Go to step 12). If wiring harness is okay, go to next step.
  7. Inspect fuel injectors and PCM connectors for damage. Repair or replace connectors as necessary. Go to step 12). If connectors are okay, go to next step.
  8. Using scan tool, check long-term fuel compensation (item 81). If long-term fuel trim value is -12.5-12.5 at 2500 RPM after engine is warmed up, go to next step. If not, go to DTC P0170  and DTC P0173  test.
  9. Using scan tool, check short-term fuel compensation (item 82). Short-term fuel trim value at 2500 RPM should be -10.0-10.0 on 2.4L or -30-25 on 3.0L after engine is warmed up. If value is as specified, go to next step. If not as specified, go to DTC P0170  and DTC P0173  test.
  10. Using a thermometer, check engine compartment ambient temperature. Using scan tool, read ECT sensor temperature (item 21). Compare both readings. If readings are not about the same, go to DTC P0115  test. If readings are about the same, go to next step.
  11. Inspect following items:
    • Check ignition coil, spark plugs and spark plug cables.
    • Check engine compression.
    • Check for skipped timing belt.
    • Check EGR valve (Federal vehicles). Go to DTC P0400  test. Repair or replace item(s) as necessary. Go to next step. If no faults are found, go to next step.
  12. Road test vehicle and attempt to duplicate conditions that caused original complaint. Recheck for DTCs. If no DTCs are displayed, test is complete.
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