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Home › Hyundai › 2000 › Sonata Base, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics - 2.4L › Diagnostic Tests › DTC P0300: Random Misfire Detected › Test Procedures

Test Procedures

  1. Turn ignition on. Connect scan tool to data link connector and verify DTC P0300 is set. If DTC P0300 is the only DTC set and fuel is at least 87 octane, go to next step. If other DTCs are set, repair other DTCs first. If fuel octane is less than 87, refuel with 87 or higher octane fuel and retest, clear DTCs and verify operation.
  2. Turn ignition off. Disconnect ignition coil connector. Turn ignition on. Measure voltage between ground and ignition coil connector terminal No. 1 (Tan/Black wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open in circuit between engine compartment junction block and ignition coil connector terminal No. 1. When repairs are completed, clear DTCs and verify operation.
  3. Turn ignition off. Disconnect ECM C44-1 (A/T) connector or C45-1 (M/T) connector. Using jumper wires, connect ignition coil connector terminal No. 3 (White wire on coil No. 1; Orange wire on coil No. 2) to ground. Measure resistance between ground and ECM C44-1 (A/T) connector terminals No. 11 and 12 or C45-1 (M/T) connector terminals No. 10 and 23. If resistance is one ohm or less, remove jumper wires and go to next step. If resistance is more than one ohm, repair open in suspect circuit between ignition coil and ECM. When repairs are completed, clear DTCs and verify operation.
  4. Turn ignition off. Disconnect ignition coils and ignition failure sensor connectors. Measure resistance between ignition failure sensor 4-pin connector terminal No. 3 (Tan/Black wire) and ignition coil connector terminal No. 1. If resistance is about one ohm or less, go to next step. If resistance is more than one ohm, repair open in Tan/Black wire between ignition coil and ignition failure sensor. When repairs are completed, clear DTCs and verify operation.
  5. Turn ignition off. Disconnect ignition coils and ignition failure sensor connectors. Measure resistance between ground and ignition failure sensor 4-pin connector terminal No. 1 (Black wire) and ignition coil connector terminal No. 2. If resistance is about one ohm or less, go to next step. If resistance is more than one ohm, repair open in Black wire between ignition coil, ignition failure sensor and/or ground connection. When repairs are completed, clear DTCs and verify operation.
  6. Turn ignition off. Reconnect ECM and ignition failure sensor connectors. Disconnect ignition coil connectors. Turn ignition to START position. Backprobe and measure voltage between ground and ignition failure sensor connector terminal No. 3 (Pink/Black wire). If voltage changes between 4-5 volts, go to next step. If voltage does not change, verify ECM connector is clean and tight. If connector is okay, replace ignition failure sensor. Clear DTC and recheck operation. If problem persists, replace ECM. When repairs are completed, clear DTCs and verify operation.
  7. Turn ignition off. Disconnect ignition coil connector and spark plug wires from coil. Measure primary coil resistance between ignition coil terminals No. 1 and 2. If primary coil resistance is about 1.3 ohms, go to next step. If primary coil resistance is not about 1.3 ohms, replace ignition coil. When repairs are completed, clear DTCs and verify operation.
  8. Turn ignition off. Measure resistance of secondary coils between ignition coil No. 1 spark plug connector terminals No. 1 and 4, and between coil No. 2 spark plug connector terminals No. 2 and 3. If secondary coil resistance is about 10,300-13,900 ohms, go to next step. If secondary coil resistance is not about 10,300-13,900 ohms, replace ignition coil. When repairs are completed, clear DTCs and verify operation.
  9. Inspect the following components/systems and ensure they are operating properly:
    • Spark plugs and spark plug wires.
    • Clogged, leaking or damaged fuel injectors and wiring.
    • Vacuum hoses and connections.

    Repair or replace components as necessary. If all components and systems are operating properly, replace ignition failure sensor. When repairs are completed, clear DTCs and verify operation.

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