Oxygen sensors (O2 sensors,
alternatively) measure...you guessed it, oxygen. More specifically,
they measure the oxygen content in the gas or exhaust. They are plunged into your exhaust both before and after your catalytic converter(s). The reason
oxygen sensors are so important is that they help your car's computer
determine the correct amount of fuel necessary for your car to idle and
run properly. When your oxygen sensors are engaged, your fuel system is
said to be in Closed Loop, which simplifies to meaning the amount of
fuel being put in is determined by the amount of oxygen being pushed
out.
So, what can go wrong when your O2 sensors aren't functioning
properly? For starters, you car can stall out. To get into Closed
Loop, your engine (specifically your engine coolant) needs to be at
normal temperature. Usually though, O2 sensors break down over time, so
before you might stall out completely, you'll notice very erratic
idling behavior. Another possibility is low fuel efficiency, as your
car will attempt to operate in Open Loop more (meaning the air to fuel
ratio is determined by the air coming into the air intake).
Depending
on your vehicle, oxygen sensors usually need replacing around 60,000 to
90,000 miles, but this can vary greatly. If you're unsure about the
status of your O2 sensors, bring your Mazda into
Parks Mazda at your convenience and we'll take a look at them for you!