My check engine light came on and it blinks once. From all the manuals and advice i get from people and honda techs, it is a bad O2 sensor. I dont know where to even look for to check if its bad or not. SO i need some help on where to look and what to do. thanks

 

First buy a manual for your car. Then try to replace it. There are two o2 sensors that could go bad. There is 1 in the cat, and 1 in the header. Both are not that hard to replace, you will need a ratchet and a 02 sensor socket. You might have ot unbolt the header to get a ratchet in there. First go here

http://www.c-speedracing.com/faq/06.php

I'm not sure where the ecu is in the newer preludes but that connector should be around the ecu. Jump the ecu connector, then find exactly what code your throwing then you know what o2 sensor is bad. Then replace it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LuckyStrikes &raquo;</TD></TR><TR><TD CLASS="quote">My check engine light came on and it blinks once. From all the manuals and advice i get from people and honda techs, it is a bad O2 sensor.</TD></TR></TABLE>
First get some better advice. There's about a zillion things that can trigger the check-engine light. Go to AutoZone & have them plug in an OBD-2 code reader. (They do it for free around here.) Have them tell you the actual code number, not just the guy's explanation for what's causing it. It'll be Pnnnn where P0nnn codes are the same for any kind of car, and P1nnn and higher are specific to Hondas.

Once you have the error code, there's a couple lists floating around here. Search because someone just posted a real good list...

Here it is...
https://honda-tech.com/zerothread?id=466877

 

the CEL blinks once and very fast, so i know its the O2 sensor, but i dont know which one of the two. and is it just plug and play when replacing it?

 

That should be the primary sensor. When you said it blinks once I thought you meant while you're driving. I guess you meant when you pull codes from your ECM...

Plug & play, but you probably should reset your ECM so it doesn't 'remember' the code.

 

where is the primary. is that the one in the header, or near the cat? and how do you reset your esu

 

Its the one on the header, and you could remove the one fuse to reset the ecu or just take the battery cable off.