I purchased new o2 sensors from Auto Zone (Bosch OE Type) and the electrical connectors are round instead of square. Does anyone know the correct part numbers for the sensors? Thanks.

 

Year, make, model, engine, trans, drivetrain, Calif. emissions?

 

2001 Dodge Ram regular cab 8 foot bed half ton 2 wheel drive 5.2 liter automatic transmission 3:55 gears, don't know if it's California emissions.

 

They may have sold you universal ones, I've had bad luck there with the lack of knowledge/understanding of parts...

With the info given, I come up with the following...

Auto Zone
O2 before converter - 13280
O2 after converter - 13280
No description of them...

Napa
O2 before converter - "OEM Type Located Before Catalytic Converter w/ Automatic Transmission Except California Emissions" - 13100
O2 after converter - " OEM Type Downstream Sensor, Located After Catalyst" - 13280

Advanced
O2 before converter - "OE Type; 4 Wire; Heated; Upstream Sensor (Before Catalytic Converter); Right side;" - 13100
O2 after converter - "OE Type; 4 Wire; Heated; Downstream Sensor (After Catalytic Converter);" - 13280

O'Reilly
O2 before converter - "OE TYPE BEFORE CATALYST" - 13100
O2 after converter - "OE TYPE AFTER CATALYST" - 13280

Auto Zone lists the same for both, 13280...obviously wrong...I don't have the same truck as you so I can't look at mine...if the part #'s they gave you start with a 15, they're universal...if the 13100 & 13280 are the #'s you've got and don't work, check the emissions label under the hood to see if it says "Federal" or "Calif." emissions...also on the same label, check the year, should say "conforms to model year 2001 emissions" or similar...if it's a different year, then start over, 'cause you just found out the actual year. If no label under the hood, check the 10th vin digit...
X = '99
Y = '00
1 = '01
2 = '02

Edit - If you bought the truck used, it may have been originally made for sale in Calif...the O2's are gonna be a totally different calibration (and therefore part #) I would assume due to the stricter emissions requirements.

 

13100 and 13280 are the sensors they sold me and they have the wrong connector.
The sticker under the hood says meets USA EPA for light duty trucks and meets California standards for medium duty vehicles.
The sticker says year 2001.
The VIN 10 digit # also says 1.
I found a webiste that sells Walker and Denso O2 sensors and there is a picture of the plug on the sensor and it looks correct so I may order them.

http://oxygensensors.com/catalog.php...s.%20NON-Calif.

 

You have California emissions...2000 and newer trucks with a GVWR less than 8500lbs. were required to comply...my 01 3/4 ton at 8800lb GVWR is not Calif. emissions...8501lb. - 14,000lb. did not have to comply 'til 2004

Point being, I'm not really sure, lotsa confusion in the aftermarket apparently...look up a 2000 in your link, since it has pics, the connectors are round...
but with the "California" on your label, it's California emissions. At least you found them...