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.

A: Hello. If the scanner indicated the O2 sens...

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: Transmission grinds, clunks, & whines on interstate

The driveshaft and final drive assembly needs to be checked. This is possibly caused by a failed center driveshaft bearing. The rubber insulator can fail and cause this type of issue. The vehicle undercarriage and driveline will need to be...

Q: Car not accelerating

This issue could be caused by something as simple as the emergency brake being left on, but that is usually the first thing that would be checked. If the emergency brake is off then there could be an issue with...

Q: I change the spark plug, cord and 02 sense but still running bad. No get up p Power light stay on.

What problem codes are set that are causing the Check Engine light? The engine may be running in "limp mode". There are many sources of poor performance, including a clogged catalytic converter, given the advanced mileage on this vehicle. But...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.