How do I know if I need an oxygen sensor replacement?

It may not be readily apparent that your oxygen sensor needs a replacement, but there are a few signs you can look for.
Your check engine light may be on to indicate the car’s system has detected an error. If the check engine light is flashing, your car has detected a major problem that requires immediate repair.
Otherwise, your oxygen sensor may need replacing if:
  • Your fuel economy is decreased
  • Your emissions levels are increasing, or you have failed an emissions test

How to replace an oxygen sensor

When you take your car to a mechanic, they will usually perform the following steps:
  • Use a code reader to see if your system is indicating a certain error
  • Check the exhaust system for vacuum holes or leaks
  • Isolate the oxygen sensor and replace it if faulty
  • Test all oxygen sensors and the exhaust system to make sure everything is working
  • Clear any error codes and reset check engine light
If the oxygen sensor stops working due to a leak in the exhaust system, a leaky vacuum or hose may need to be repaired or replaced, which can increase your repair bill.

How important is an oxygen sensor replacement?

Your car has oxygen sensors at each cylinder (and often at each catalytic converter) to monitor the oxygen levels in the air-fuel mix that flows through your engine and out the exhaust pipe.
When an oxygen sensor detects that the air-fuel mix is too rich, it will send a signal that causes the fuel to be cycled through again before release, lowering your car’s emissions.
Oxygen sensors that are working improperly can cause you to fail an emissions test, decrease your fuel economy, or even lead to engine damage in the long term. For this reason, it’s optimal to take your car in for an inspection or replacement as soon as you notice an issue.

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