Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 704 (ENGINE CONTROL SYSTEM & FUEL SYSTEM - 2.4L - DTC P0010 TO DTC P0366)DTC P0300-P0304CIRCUIT/SYSTEM TESTING
2006 Chevrolet Cobalt SS, 4D Sedan, Standard
Circuit/System Testing
2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
- Verify that the following conditions do not exist:
- Engine vacuum leaks
- Fuel pressure that is too low or too high-Refer to Fuel System Diagnosis .
- Contaminated fuel-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Restricted exhaust system-Refer to Restricted Exhaust .
- If you find any of the above conditions, repair as necessary.
- Ignition OFF, remove the ignition coil from the misfiring cylinder, leaving the electrical connector connected.
- Install the J 26792 (SA91992) to the boot of an ignition coil and ground.
- Attempt to start the engine and observe the J 26792
(SA91992). The spark tester should spark.
- If there is no spark, refer to Electronic Ignition (EI) System Diagnosis for diagnosis of the ignition coil.
- Ignition OFF, remove the spark plug from the misfiring cylinder. Verify that the following conditions do not exist with the spark plug:
- Gas, coolant, or oil fouled
- Cracked, worn, incorrectly gapped-Refer to Spark Plug Inspection .
- If there is a condition with the spark plug, replace the spark plug.
- Exchange the suspected spark plug with another cylinder that is operating correctly.
- Operate the engine under the conditions in which the misfire occurred. Observe the Misfire Current Counters with a scan tool. The misfire should not follow the spark plug exchange.
- If the misfire follows the spark plug, replace the spark plug.
- If all conditions test normal, test or inspect for the following:
- A lean or rich fuel injector-Refer to Fuel Injector Diagnosis (w/CH47976) or Fuel Injector Diagnosis (w/J39021 or w/Tech 2) .
- An engine mechanical condition-Refer to Symptoms - Engine Mechanical .
IMPORTANT:
An erratic or weak spark is considered a no spark condition.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.