Oxygen (O2) sensors in your vehicle are important for two simple reasons. The first reason is that a faulty oxygen sensor will cause unnecessary fuel consumption, lowering the effective gas efficiency of your vehicle and costing you more bucks while your car spews excessive levels of exhaust into the air. The second reason is that a faulty oxygen sensor will cause your check engine or service engine indicator to light up, in which case, your vehicle will likely fail inspection. Replacing oxygen sensors is not the most cumbersome task you will encounter. However, even the most simple error could cause you to spend more time and money than the job requires. Follow these tips to give yourself the least amount of headache in dealing with faulty oxygen sensors.
The best way to diagnose a faulty O2 sensor is via your vehicle’s onboard diagnostics (OBD) which outputs diagnostic trouble codes that allow identification of the specific issue. A scan tool is required to read out these codes and this an be done at a nearby mechanic or auto parts store, usually for free. For example, if your vehicle outputs the code P0161, it means that your oxygen sensor in bank 2 sensor 2 is probably malfunctioning. If the code read is P0141, then it is referring to a faulty oxygen sensor in bank 1 sensor 2. The number of oxygen sensors vary depending on the vehicle type and their locations within the vehicle vary as well. So make sure you know exactly where the relevant oxygen sensor is located before you take steps to purchase a new O2 sensor, or even before you take it to get fixed at a mechanic. You can easily find the O2 sensor configuration for your vehicle by searching online.
One other thing to note is to make sure you know which type of emissions, federal or California, your vehicle conforms to. Generally this information can be found under your hood, or somewhere within the engine compartment. This is important when you purchase your replacement oxygen sensor, which is manufactured separately for federal and California emission standards.