Skip the auto shop - Our mechanics make house calls

Q: after replacing spark plugs and wires engine light still come on should i replace the O2 sensor as diagnose suggested if so which

asked by on

Engine light on after repacing sparkplugs and wires which sensor do i change as suggested by diagnostic test give by autopart store?

My car has 120000 miles.
My car has an automatic transmission.

Hello. If the scanner indicated the O2 sensor was bad, I would recommend replacing. The oxygen sensors are located in the exhaust system of the engine, and they sense the oxygen content of the exhaust gases. There should be two O2 sensors on this model engine, one on either side of the catalytic converter.

The sensor located just in front of the catalytic converter measures the mixture of the exhaust gas exiting the engine. The sensor located after the catalytic converter is used to measure the performance of the converter by comparing the O2 levels before and after. (Upstream is the same as pre-catalyst, before the catalytic converter. Downstream is post-catalyst or behind the catalytic converter). The amount of oxygen in the exhaust varies according to the air/fuel ratio of the fuel injection system. The oxygen sensor produces a small voltage signal that is interpreted by the electronic control unit (ECU) of the fuel injection system. The ECU makes constant adjustments in fuel delivery according to the signal generated by the oxygen sensor in order to maintain the optimum air/fuel ratio. If you would like to have this done, a certified technician from YourMechanic can come to your car’s location to replace the oxygen sensor if needed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  • Home
  • Questions
  • after replacing spark plugs and wires engine light still come on should i replace the O2 sensor as diagnose suggested if so which

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How much to fix a fan clutch

Hi there. The fan clutch controls how quickly the cooling fan spins against the radiator. The hotter the engine gets, the more the fan has to spin. If the fan clutch is not functioning correctly, the fan won’t spin at...

Q: Code P0720 and truck does not shift normally.

Hi there. The code that you are getting is for the output speed sensor of the transmission. I change quite a few of these as they are a common issue. I would have this replaced first and clear the codes....

Q: Hey Peter i have a 99 Lincoln Town Car that decreases acceleration when driving then back to normal when i stop what is this probl

Hi there. A lack of acceleration can be caused by multiple issues, ranging from fuel system restrictions to ignition system problems. Without knowing for certain what is causing this problem, it's not possible to provide a repair solution. The best...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.