This is an article on how to replace a camshaft position sensor on a sunfire or cavalier 2.2 liter engine. The engine uses this for the timing of the engine and without it, the engine may not run at all. The cam position sensor could also intermittenly cause running or starting issues. If the engine backfires from another problem, it could cause the computer to show an error even if the sensor is working correctly. The arrow in the picture points in the general location of the camshaft sensor which is located on the backside of the engine. First you will need to remove the top air hose which is also located in front the arrow.
Oxygen sensors also known as o2 sensors will go bad somewhere around 60,000 miles. When an oxygen sensor goes bad your check engine light will come on. You will need to have your computer scanned, autozone does this for free. Most newer cars, especially 1996 and newer vehicles will have two o2 sensors. Scanning the computer will tell which o2 sensor is bad. The primary o2 is located in the exhaust header manifold. It is visible in this picture in the bottom, slightly left of the middle. The secondary oxygen sensor will be located next to the catylitic converter. The location of the two sensors are generally the same on all vehicles. This vehicle is a 2001 2.2 liter chevy cavalier.
An air temperature sensor is used on fuel injected engines. The purpose of an air temperature sensor is to help the computer calculate air density. A change in temperature changes the resistance in the sensor. Simply stated, the higher the air temperature gets the less dense the air becomes. As the air becomes less dense the computer knows that it needs to lessen the fuel flow. If the fuel flow was not changed the engine would become rich, possibly losing power and consuming more fuel. The temp sender is generally located in the air inlet tube or the air box. The wire running to the sensor can be disconnected then the sensor can be unscrewed and replaced. Some aftermarket companies trick this sensor with a resistor (false temp reading) to make the engine run richer. If a engine has been tuned lean this trickery can show mild power gains.