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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 99 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0300, DTC P0301, DTC P0302, DTC P0303, DTC P0304, DTC P0305, DTC P0306, DTC P0307 Or DTC P0308 >> Diagnosis & Repair (Using OBD-II Scan Tool)

Diagnosis & Repair (Using OBD-II Scan Tool)

WARNING: This page is about a different car, the 2003 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
  1. If any other codes (besides DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308) are being output, diagnose other DTC first. If no other DTCs are output, go to next step.
  2. Check the connection conditions of wire harness and connector. Check for disconnection of piping and break of vacuum hose. Repair as necessary. If okay, go to next step.
  3. Check connection of PCV piping. Repair or replace PCV piping as necessary. If okay, go to next step.
  4. Disconnect the ignition coil with igniter. Remove the spark plug. Check the spark plug type and electrode gap. Ensure recommended spark plug is installed and electrode gap is 0.043" (1.10 mm). Disconnect the ignition coil with igniter connector, and disconnect the ignition coil with igniter. Remove the spark plug. Install the spark plug to the ignition coil with igniter, and connect the ignition coil with igniter connector. Disconnect the injector connector. Ground the spark plug. Check if spark occurs while the engine is being cranked for 5-10 seconds. If spark jumps across electrode gap, go to step  7. If spark does not jump across electrode gap, go to next step.
  5. Disconnect the spark plug. Change the spark plug. Install the spark plug to the ignition coil with igniter. Disconnect the injector connector. Ground the spark plug. Check if spark occurs while the engine is being cranked for 5-10 seconds. If spark jumps across electrode gap, replace spark plug. If spark does not jump across electrode gap, go to next step.
  6. Check for open and short in harness and connector between ignition coil with igniter and ECM. If okay, replace ignition coil with igniter, then confirm that there is no misfire. If not okay, repair or replace harness or connector.
  7. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM connector and measure voltage between ground and fuel injector terminals at specified ECM connector. See IDENTIFYING FUEL INJECTOR TERMINALS  table. See Figure. If voltage is 9-14 volts at each terminal, go to step  10. If voltage is not 9-14 volts at each terminal, go to next step. If using oscilloscope, with engine idling, check the waveform between terminals No. 1-8 and E01 of the ECM connectors. See Figure and Figure .
  8. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is not as specified, replace fuel injector. If resistance is as specified, check for open or short in wiring between ECM and fuel injector. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If problem exists, repair as necessary. If problem does not exist, repair open or short in injector power source circuit.
  9. Check for open and short in harness and connector between ignition switch and injector, injector and ECM of misfiring cylinder. Repair or replace as necessary. If okay, go to next step.
  10. Check fuel injectors. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING - LX470 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  11. Check engine compression. See BASIC DIAGNOSTIC PROCEDURES article. If engine compression is okay, check valve clearance. See ON-VEHICLE ADJUSTMENTS article. If valve clearance is okay, it may be necessary to check valve timing. See appropriate ENGINES article.
  12. Check valve clearance of misfiring cylinder. Adjust valve clearance as necessary. If okay, go to next step.
  13. Check valve timing. Check for loose and jumping teeth of timing belt. Adjust valve timing as necessary. If okay, go to next step.
  14. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES - LX470 article. Repair as necessary. If okay, go to next step.
  15. Check mass airflow sensor. See AIRFLOW METER under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - LX470 article. Repair as necessary. If okay, go to next step.
  16. Check engine coolant temperature sensor. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR under SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - LX470. Replace sensor as necessary. If okay, check for intermittent problems.
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