Where is the O2 Sensor located?

BUSINESSFRED

MEMBER
2014 NISSAN SENTRA
1.8L
4 CYL
2WD
AUTOMATIC
178,000 MILES

I am replacing the o2 sensor with an OEM Part because the monitor is not ready for the emissions test here in California.

I am requesting a diagram to locate the Heated Oxygen Sensor and Oxygen sensor, I'm not sure how to tell the two sensors apart and want to make sure I'm replacing the right one.

The HO2S monitor works but the O2 sensor monitor is not ready even after 10,000 miles and Over 300 drive cycles.

3 Replies

AL514

MECHANIC
4,201 POSTS

Hello, the front sensor (before the Catalytic Converter) is an A/F ratio sensor, air/fuel ratio sensor and is a wideband type sensor, the rear oxygen sensor is a narrowband oxygen sensor. They both work differently. Are any codes setting in the engine control module (ECM)? I'll post the wiring diagrams to identify the two sensors. There should be a code setting if the Readiness monitors are not passing.

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Wednesday, May 15th, 2024 AT 2:15 PM

AL514

MECHANIC
4,201 POSTS

Here are the wiring diagrams for the oxygen sensors, the 2nd one is the OEM diagram. But if you have access to a scan tool, I would check the live engine data to see if there are any codes stored, or if the engine is running rich or lean. The Long Term and Short Term Fuel Trims will tell you a percentage, either positive or negative, and this is the amount of compensation the ECM is making for a rich or lean condition.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

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