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Home >> Hyundai >> 2001 >> XG300 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300: Random Misfire Detected >> Test Procedures
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Test Procedures

  1. Check if any DTC other than P0300 is set. If only DTC P0300 is set, go to next step. If any other DTC is set, repair that DTC first. See appropriate DTC test under DIAGNOSTIC TROUBLE CODE (DTC) DEFINITIONS .
  2. Check fuel octane. If fuel octane is 87 or more, go to next step. If fuel octane is less than 87, refuel with 87 or higher octane fuel. When repairs are completed, clear DTC and verify DTC P0300 no longer sets.
  3. Turn ignition off. Disconnect each ignition coil 3-pin connector. Turn ignition on. Measure voltage between ground and each ignition coil connector terminal No. 1 (Pink/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Pink/Black wire between appropriate ignition coil and IGNITION COIL fuse (20-amp) located in engine compartment junction block. When repairs are completed, clear DTC and verify DTC P0300 does not set.
  4. Turn ignition off. Disconnect PCM connector C44-1. See Figure. Using jumper wires, ground each ignition coil connector terminal No. 3. Measure resistance between ground and PCM connector C44-1 terminals No. 12 (Orange wire - ignition coil No. 1), No. 11 (White wire - ignition coil No. 2), and No. 13 (Green/White wire - ignition coil No. 3). If each resistance is one ohm or less, go to next step. If any resistance is more than one ohm, repair open in appropriate wire between ignition coil and PCM. When repairs are completed, clear DTC and verify DTC P0300 does not set.
  5. Remove jumper wires. Disconnect ignition failure sensor 4-pin connector. Measure resistance of Black wires between ignition failure sensor connector terminal No. 1 and each ignition coil connector terminal No. 2. If each resistance is one ohm or less, go to next step. If any resistance is more than one ohm, repair open in Black wire between appropriate ignition coil and ignition failure sensor. When repairs are completed, clear DTC and verify DTC P0300 does not set.
  6. Measure resistance between ground and ignition failure sensor connector terminal No. 1 (Black wire). If resistance is one ohm or less, go to next step. If resistance is more than one ohm, repair poor ground or open in Black wire between ignition failure sensor and ground. When repairs are completed, clear DTC and verify DTC P0300 does not set.
  7. Reconnect PCM connector. While briefly holding ignition switch in START position, measure voltage between ground and each ignition coil connector terminal No. 3 (Orange wire on ignition coil No. 1; White wire on ignition coil No. 2; Green/White wire on ignition coil No. 3). Voltage should vary between 5 volts and 4 volts while engine is cranking. If each voltage is as specified, go to next step. If any voltage is not as specified, check PCM connector for loose or damaged terminals. If problem exists, repair connector. If problem does not exist, replace power transistor. Clear code and verify DTC P0300 does not set. If DTC P0300 sets, replace PCM. When repairs are completed, clear DTC and verify DTC P0300 does not set.
  8. Turn ignition off. Disconnect spark plug wires from ignition coils. Measure primary coil resistance between ignition coil connector terminals No. 1 and 2 (component side). Primary coil resistance should be about 1.3 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace ignition coil. When repairs are completed, clear DTCs and verify DTC P0300 does not set.
  9. Measure resistance of secondary coils between ignition coil towers for spark plug wires No. 1 and 4, between ignition coil towers for spark plug wires No. 2 and 5, and between ignition coil towers for spark plug wires No. 3 and 6. Secondary coil resistance should be 10,300-13,900 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace ignition coil. When repairs are completed, clear DTCs and verify DTC P0300 does not set.
  10. Inspect the following components/systems and ensure they are operating properly:
    • Spark plugs and spark plug wires.
    • Fuel injectors.
    • Vacuum hoses.

    If problem exists, repair as necessary. If problem does not exist, replace power transistor. When repairs are completed, clear DTCs and verify DTC P0300 does not set.

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