Will My Car Start With a Faulty 02 Sensor?

by Andrea Stein
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Automotive engines rely on electronic devices, such as oxygen sensors, to help a car to efficiently. A faulty oxygen sensor not only will limit your car's computer's ability to regulate fuel burning optimally, it can negatively impact the engine to a point that it inhibits the car’s ability to start properly.


An O2 sensor, or oxygen sensor, is a device typically screwed into a car’s exhaust manifold to gauge the oxygen amount contained in exhaust gases. The car’s ECU, or engine computer unit, reads these measurements and uses them to help control the operation of the internal combustion engine. The amount of oxygen in the exhaust determines how the computer manipulates the fuel and air mixture to burn as clean as possible.


An oxygen sensor can fail over time and give faulty readings to engine computer unit, causing it to add or decrease more fuel than necessary to the air/fuel mixture. That will cause more pollutant emissions and lowered fuel efficiency. Oxygen sensors can also be contaminated from coolant leaks or lead from leaded gasoline, and by environmental factors such as road grime or moisture.


In many cases a car will start with a faulty O2 sensor, but the sensor may cause the car to backfire or stall while idling. A faulty O2 sensor also can cause so little fuel to be sent to the engine that the car may not start.

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