Check Engine Light On? How to Tell if It's the Ignition Coil or O2 Sensor
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Seeing that yellow "Check Engine" light can be stressful. Before you panic, here is a quick rule of thumb to diagnose whether your car needs Ignition Coils or O2 Sensors—saving you a trip to the mechanic.
1. Symptoms of a Failing Ignition Coil
· Rough idling or jerking during acceleration.
· Engine misfires (you will feel a stutter).
· Trouble starting the engine.
· OBD Code: Usually P0300 - P0306 (Misfire detected).
2. Symptoms of a Failing O2 Sensor
· Decreased fuel mileage (suddenly visiting the gas station more often).
· Rotten egg smell from the exhaust.
· Failed emission tests.
· OBD Code: Usually P0130 - P0161 (Oxygen sensor circuit malfunction).
Still unsure? Use an OBD2 scanner. If the code says "Misfire," it is likely the Ignition Coil. If it says "System Too Lean/Rich," it is likely the O2 Sensor.