I recently ordered a bunch of clearance O2 sensors from RA for various cars; from 13 bucks to 18 bucks.
What I received were sensors in matching packages, but made by different manufacturers.
2 95 Honda accord sensors, came in matching Beck Arnley boxes, and were matching Densos (with diff length wires)
4 Hyundai Sonata sensors, two came sealed in Genuine Hyundai Parts bags, and both were NTK equivalent- one was actually an NTK (4ohm heater) and the other was anNTK knockoff by some Korean company called "golden". They were phyiscally identical. The NTK unit worked perfectly, the Golden unit was damaged from the package, two of 4 wires were broken inside the sheaths RIGHT at the sensor base, leaving no wire to strip and repair. I used pins stuck into the stumps with wires soldered onto them for testing. The heater on the GOLDEN sensor worked, but no output from the sensor. Given the dents on the GOLDEN housing, I assume it was sabotaged or damaged as a recovery part, which was subsequently sold to RA.
Two more sensors came, in Beck Arnley boxes. They did not match albeit being for the same application. One was a BOSCH knockoff made by GOLDEN, and the other was some other style of sensor, again made by GOLDEN. The Bosch Golden had outputs that looked good on a meter, but did not jive with the ECU. The other sensor, again great heater, correct resistance, but no sensor output at all.
In conclusion, I got the shaft. Out of 6 sensors, 3 were brand name (Denso and NTK) and were the only ones that worked. I have no desire to return them or grapple with RA over it.
Installed the pair of working Densos in a Pontaic G6, they work GREAT except for OBD2's horrible whineyness- OBD2 is unhappy that the heater circuits on the Densos are 14ohm, instead of 5ohm. So despite perfect sensor output and improved fuel economy, it throws a CEL. Eventually I'll purchase a match for that NTK (with correct resistnce) and install that pair.
So be careful with closeouts @ Rock Auto!