How many 02 sensors?

[Classicswc]

I have a 2001 1500 with the 5.9 engine. Everything I've read states there are 2 upstream sensors. Not on my truck, there is only 1, directly in front of the cat. What gives?

 

[crash68]

If the truck has a single exhaust or it's not a California emissions vehicle it will have two O2 sensors. Cali and dual exhaust truck should have four.

 

[Fast69Mopar]

I have a 2001 1500 with the 5.9 engine. Everything I've read states there are 2 upstream sensors. Not on my truck, there is only 1, directly in front of the cat. What gives?

Have you looked at the build sheet for your truck to see where it was built and where it was located when it's "in-service" date occurred?

I have seen a few trucks in my time as a dealership level tech that were built in early 2000 and late 2001 that only had the upstream oxygen sensor installed. The connector for the downstream oxygen sensor was still in the harness on the right side of the trans but it had never been connected to anything.

All of the data in the DRB-III was normal except for 0.0V for the 1/2 O2 sensor.

 

[Classicswc]

Thanks. I ran my hands over every inch from the manifold to the cat, only one sensor.

 

[Ajdero5]

I have the same issue. Have a 2001 titled truck sticker on the door says sometime in 2000 September or later. I have only one plug, round 4 pin, the upstream sensor plug I would assume. has a aftermarket exhaust with bungs on upstream and downstream for the sensors to thread into but they're plugged. Only code it's throwing is the sensor code bc the computer thinks it's not heating up/running. Runs great just idles rough sometimes after it warms up. I'm wondering if I need to/should get a sensor to plug in or if it's not worth it? How else would I get the light to go away

Thanks. I ran my hands over every inch from the manifold to the cat, only one sensor

 

[tron67j]

I had a 2003 2500 with the 5.7 engine and the upstream O2 sensor and cable were bad. It vexed the dealership for why there was only one upstream sensor because they replaced it and still had an error code, which led to replacing the cable. They looked for a second sensor but there was none. They received a response from somewhere above that a few early 2003 2500s were turned to run the single O2 upstream sensor setup from the 5.9. I owned the truck from new, original exhaust, and ran every inch of the system from engine to tailgate to count the sensors, only one upstream sensor.