Chevrolet Trax: DTC P0300-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 P0300

Engine Misfire Detected

DTC P0301

Cylinder 1 Misfire Detected

DTC P0302

Cylinder 2 Misfire Detected

DTC P0303

Cylinder 3 Misfire Detected

DTC P0304

Cylinder 4 Misfire Detected

Circuit/System Description

The engine control module (ECM) uses information from the crankshaft position sensor and the camshaft position sensor to determine when a engine cylinder misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM can detect individual cylinder misfire events.

Extreme cylinder misfire events can cause catalytic converter damage. The malfunction indicator lamp (MIL) will flash when the conditions for catalytic converter damage are present. DTCs P0301 through P0304 correspond to cylinders 1 through 4. When the ECM detects that a specific cylinder is misfiring, a DTC for the that cylinder will set and the corresponding fuel injector is disabled. The ECM will re-enable the fuel injector after 3 crankshaft revolutions if equipped with an automatic transmission or 6 crankshaft revolutions if equipped with a manual transmission to determine if the misfire is still present. If the misfire is still present, the ECM will disable the fuel injector again after 3 crankshaft revolutions if equipped with an automatic transmission or 6 crankshaft revolutions if equipped with a manual transmission repeating the process. If the misfire is not present, the fuel injector will remain enabled by the ECM.

Conditions for Running the DTC

• DTCs P0016, P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0222, P0223, P0315, P0335, P0336, P0502, P0651, and P2135 are not set.
• The engine speed is greater than 1000 RPM.
• The crankshaft and camshaft are syncronized.
• The ignition voltage is between 11-18 V.
• The engine coolant temperature (ECT) sensor is between -7 to +125ºC (+19 to +257ºF).
• 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.

The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTC

P0300

The ECM detects a crankshaft rotation speed variation indicating a misfire rate sufficient to cause emissions levels to exceed a predetermined value or a misfire rate high enough to cause catalyst damage.

P0301, P0302, P0303, or P0304

The ECM detects a crankshaft rotation speed variation indicating a single cylinder misfire rate sufficient to cause emissions levels to exceed mandated standards.

Action Taken When the DTC Sets

• DTCs P0300, P0301, P0302, P0303 and P0304 are Type B DTCs.
• The malfunction indicator lamp (MIL) will flash when the conditions for catalytic converter damage are present

Conditions for Clearing the DTC

DTCs P0300, P0301, P0302, P0303 and P0304 are Type B DTCs.

Diagnostic Aids

• A misfire DTC could be caused by an excessive vibration from sources other than the engine. Inspect for the following possible sources:

• A tire or wheel that is out of round or out of balance
• Variable thickness brake rotors
• An unbalanced drive shaft
• Certain rough road conditions
• Transmission operation
• Cracked Spark Plug Insulators
• Broken or weak valve spring
• A damaged or defective accessory drive component or belt; remove the belt and safely operate the engine to evaluate if misfire counts go away.

• 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.

• If the condition is intermittent, observing the scan tool IC Circuit Test and Fuel Injector Circuit Test Status parameters may help isolate the condition. The circuit test status parameters will change from OK or Not Run to Fault/Malfunction if a condition exists.
• A condition in the heated O2 sensor (HO2S) heater control circuits may set a DTC P0300.

Reference Information

Description and Operation

• Electronic Ignition System Description
• Fuel System Description (LUJ) , Fuel System Description (LUV)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL 26792 HEI Spark Tester

For equivalent regional tools, refer to Special Tools (Diagnostic Tools) .

Circuit/System Verification

NOTE: Before starting the engine, review the freeze frame failure records data to determine if the misfire sets during a cold start or at operating temperature. If there is a cold start condition and the engine is started, the engine will need to be cooled down before the next attempt to start the engine within the fail conditions.

1. Engine Running at normal operating temperature.
2. Verify there is no abnormal engine noise.

• If abnormal engine noise is present

Refer to Symptoms - Engine Mechanical .

• If abnormal engine noise is not present

3. Perform the scan tool Crankshaft Position System Variation Learn procedure.
4. Verify no DTCs are set.

• If any DTCs other than P0300-P0304 are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

• If DTC P0300-P0304 is set

Refer to Circuit/System Testing.

• If no DTCs are set

5. Verify the scan tool Cylinder 1-4 Current Misfire Counter parameters do not increment.

• If increments

Refer to Circuit/System Testing.

• If does not increment

6. Engine Running, perform the Cylinder Power Balance Test with a scan tool.
7. Verify the engine speed changes when each injector is disabled and then enabled.

• If engine speed does not change

Refer to Circuit/System Testing.

• If engine speed does change

8. 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 data.
9. Verify the DTC does not set.

• If the DTC sets

Refer to Circuit/System Testing.

• If the DTC does not set

10. All OK.

Circuit/System Testing

1. Verify none of the following conditions listed below exist:

• Damage, carbon tracking, or fluid intrusion of the spark plug boots and/or spark plugs
• Vacuum hose splits, kinks, and incorrect connections
• Engine vacuum leaks
• Crankcase ventilation system for vacuum leaks
• Fuel pressure that is too low or too high. Refer to Fuel System Diagnosis (LUJ) , Fuel System Diagnosis (LUV) .
• Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
• Exhaust system restrictions
• If a condition exists

Repair or replace as necessary.

If no conditions exist

NOTE: An erratic or weak spark is considered a no spark condition

3. Ignition OFF, remove the K35 Ignition Coil Module from the spark plugs and connect the EL 26792 HEI Spark Tester to the appropriate spark plug boot, engine Cranking.
4. Verify the spark output.

• If no output or the output is weak

Refer to Electronic Ignition System Diagnosis .

• If the output is good

5. Ignition OFF.
6. Verify the conditions listed below. Refer to Ignition System Specifications .

• The correct spark plug type
• The correct spark plug gap
• The correct spark plug torque
• If a condition exists

Repair or replace as necessary.

• If no conditions exist

7. Exchange the suspect spark plug with another cylinder that is operating correctly.
8. Engine Running.
9. Verify the scan tool Cylinder 1-4 Current Misfire Counter does not increment for the cylinder where the suspect spark plug was installed.

• If increments

Replace the spark plug.

• If does not increment

10. Test or inspect for the conditions listed below:

• A lean or rich Q17 Fuel Injector-Refer to Fuel System Diagnosis (LUJ) , Fuel System Diagnosis (LUV) .
• An engine mechanical condition-Refer to Symptoms - Engine Mechanical

Repair Instructions

• Ignition Coil Replacement
• Spark Plug Replacement

Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced
3. Clear the DTCs.
4. Turn OFF the ignition for 60 s.
5. If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.
6. Engine Running, verify the scan tool Cylinder 1-4 Current Misfire Counter parameters do not increment.

• If the misfire counter parameters increment, a misfire condition still exists.

7. To verify that the performance of the catalytic converter has not been affected by the condition that set this DTC, perform the Repair Verification for DTC P0420. Refer to DTC P0420 .

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