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DTC P0301-P0304

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0301 00: Cylinder 1 Misfire Detected

DTC P0302 00: Cylinder 2 Misfire Detected

DTC P0303 00: Cylinder 3 Misfire Detected

DTC P0304 00: Cylinder 4 Misfire Detected

Circuit/System Description

The engine control module (ECM) uses information from the crankshaft position sensor in order to determine when an engine misfire is occurring and uses information from the camshaft position sensor - inlet and camshaft position sensor - exhaust sensors in order to determine which cylinder is misfiring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. DTCs P0301 00 - P0304 00 correspond to cylinders 1-4. If the ECM is able to determine that a specific cylinder that is misfiring, the DTC for that cylinder will set.

Conditions for Running the DTC
    • The engine speed is between 600-6 528 RPM.
    • The ignition voltage is between 11-18 V.
    • The engine coolant temperature (ECT) is between -7 to +125°C (+19 to +257°F).
    • The A/C compressor clutch is not changing states.
    • The fuel tank level is greater than 15%.
    • The ECM is not in fuel cut-off or deceleration fuel cut-off mode.
    • The ECM is not receiving a rough road signal.
    • The throttle angle is steady within 5%.
    • The throttle angle is greater than 3% when the vehicle speed is greater than 5 km/h (3 mph).
    • The transmission is not changing gears.
    • The antilock brake system (ABS) and the traction control system, if equipped, is not active.
    • DTCs P0301 00, P0302 00, P0303 00, and P0304 00 run continuously when the above conditions are met.

Conditions for Setting the DTC

The ECM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission or catalyst damaging levels to exceed mandated standards.

Action Taken When the DTC Sets

DTCs P0301 00, P0302 00, P0303 00 and P0304 00 are Type A (MIL flashing) or Type B DTCs.

Conditions for Clearing the DTC

DTCs P0301 00, P0302 00, P0303 00 and P0304 00 are Type A (MIL flashing) or Type B DTCs.

Diagnostic Aids
    • A misfire may only occur when the engine is under a load or when the engine is cold.
    • A misfire DTC may be caused by an excessive vibration from sources other than the engine. Inspect for the following possible sources:
       - A tyre or wheel that is out of round or out of balance
       - Variable thickness brake rotors
       - Certain rough road conditions
       - A damaged accessory drive component or belt
       - A damaged reluctor wheel
    • High resistance in the circuits of the injectors may set a misfire DTC without setting an injector DTC. Test the injector circuits of the affected cylinder(s) for a high resistance if you suspect a condition.
    • The MIL indicator flashes when there is an engine misfire.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EN 36012-A Ignition System Diagnostic Harness

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification
  1. Engine running at the normal operating temperature, verify there is no abnormal engine noise.
    2. ⇒If there is an abnormal engine noise, refer to Symptoms - Engine Mechanical

    Note: A misfire may only occur when the engine is under a load. An engine load may be necessary to verify the condition.

  2. Observe the scan tool Misfire Current Counter parameters. The Misfire Current Counters should not be incrementing.
  3. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

Circuit/System Testing
  1. Verify that the following conditions do not exist:
    2. • Vacuum hose splits, kinks, and incorrect connections
    • Engine vacuum leaks
    • Crankcase ventilation system for vacuum leaks, refer to Crankcase Ventilation System Inspection/Diagnosis .
    • Fuel pressure that is too low or too high, refer to Fuel System Diagnosis .
    • Restricted exhaust system, refer to Restricted Exhaust .
         ⇒If you find any of the above conditions, repair as necessary.
  2. Ignition OFF, disconnect the harness connector at the appropriate Q17 Fuel Injector.
  3. Connect a test lamp between the control circuit terminal 2 and the ignition voltage circuit terminal 1.
  4. Engine idling, the test lamp should flash.
    5. ⇒If the test lamp does not flash, refer to Engine Controls Schematics .
  5. If all conditions test normal, test or inspect for the following:
    6. ⇒An engine mechanical condition, refer to Symptoms - Engine Mechanical .

Repair Instructions

Fuel Injector Removal

Repair Verification
  1. Clear the DTCs with a scan tool
  2. Turn OFF the ignition for 60 s.
  3. Start the engine.
  4. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records.
  5. If the DTC fails this ignition, a misfire still exists.
   


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