I drive a 1997 Honda Civic LX Manual transmission and my buddy mechanic said the check engine codes indicate that I need a new upstream o2 oxygen sensor. I was told that Denso is the way to go, but could someone please let me know which one I should get? What is the difference between the 234-4209 and the 234-4065? I also see a 234-4099? I've seen some crazy oxygen sensors for over $100, then I've seen some generic for less that $20. If someone with more experience could provide some advice I would greatly appreciate it. Thanks!

 

get one for a Honda civic, 4 wire, with an oem connector (not just bare wires at the end), and you shouldn't have any problems. 234-4099 should be fine. I am seeing prices around $25 on rockauto.com.

I didn't look into the part numbers too much, but I'm sure the cheapest one is the sensor without a connector on it, which can make installation a pain when you are splicing wires, hoping to match the colors.

 

234-4099 is Upstream O2 sensor OE style
234-4029 is Upstream O2 sensor Universal
234-4065 is Downstream O2 sensor OE style

So, I'd recommend the 4099 since it's direct fit and OE style.
Amazon and RockAuto will be your best sources.