Check engine light - Oxygen sensor?

VASEAN19

MEMBER
1996 HYUNDAI ELANTRA

Hi. I have a quick question. When I bought my car used from a dealer the engine light was already on. Last week the car had a problem and the engine light was blinking. I took it to a mechanic and had something fixed and when I got the car out the shop the engine light wasn't on. Now today the light is back on. They say the primary O2 sensor is bad how can I change it out?

Monday, March 15th, 2010 AT 6:09 AM

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,

Replacing the oxygen sensor can be done with simple hand tool in relatively short period of time.
Your vehicle has 2 oxygen sensors. One before the catalytic converter and one after the catalytic converter.
The primary oxygen sensor is the one before the catalytic converter.
It is the one between the exhaust manifold and the catalytic converter.
See the picture below, it is the one marked as 'upstream'.

Here are some helpful articles on oxygen sensor, including basic replacement procedure:

https://www.2carpros.com/articles/how-an-oxygen-sensor-works
https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor
https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

Please let me know of any questions.

Thank you.

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