I have a 98 Civic EX and for the last few months the primary O2 sensor keeps going bad. Back in 2002 I got a new DC header and Greddy exhaust and up until 5/2006 they didn't cause any trouble. In May of 2006 my primary O2 sensor went bad and it was replaced by Honda. They told me it was routine that it went bad. Then last week the same O2 sensor (Bank 1, sensor 1) went bad again. Since it was replaced 3 months ago, Honda replaced it again for free. But they said it was caused by my aftermarket header and exhaust so if it broke again it would not be covered anymore. Today the check engine light is on in my car again today and I think it's going to be the same issue again. I have to take it in tomorrow to be sure, but I just wanted to see if anyone on these forums had any info. I'm not sure if the aftermarket parts could keep breaking the sensor or if I need to purchase a Honda made header and exhaust. I just can't afford to keep dropping my car off and paying for service fees over and over. Thank you.

 

well one way to avoid the service fees is to learn how to do it yourself. as for the o2 sensor, it sounds weird that the headers will cause this. what type brand of o2 sensor is it? also are you sure this time it's the primary sensor and not the secondary? they should be replaced about every 100,000 miles. are you in that range?

 

thats something i've never heard of, a header ruining an o2 sensor. if they put too moch anti-seize on threads that could possibly ruin it.

 

I'm not sure exactly what brand of O2 sensor it is. The service department at my local Honda dealership ordered it when I took my car in. Here's the mileage on my car for each occurence.
50,000: Added aftermarket header, exhaust, cold air intake.
101,345: Primary O2 sensor broke and was replaced.
103,102: Primary O2 sensor broke and was replaced (Under warranty from the last time). Was told it wouldn't be covered if it happened again because the aftermarket parts are probably causing it.
103,354: Check engine light is on again.
The tech told me the header could be getting too hot and frying the O2 sensor. Both of the times it was replaced, it was the same O2 sensor (Bank1,Sensor1).

 

Do you use a lot of silicone based cleaners/products in the engine compartment. or near the cold air intake? The reason I ask is that when silicone vapor is burned the byproduct damages the O2 sensor. In a very short period of time. This is why my friend was going through O2 sensors on i=his car about once a month. once he stopped using silicone cleaners in the engine bay his car stopped burning up O2 sensors

 

Nope, I don't use any silicone-based cleaning products.

 

The service department tested my car this morning. It is the same O2 sensor again, although the aren't sure if the O2 sensor is even broken, they think it might be too far away from its normal position and the readings are off. The DC header I have in my car puts the O2 sensor too close to the catalytic converter. I don't see how this can be the reason, because the O2 sensor was fine for over 3 years before in the same exact position. They say my options are either buy a Honda header for $900 or mount the O2 sensor closer to where it should be(but it would need to be welded). Any thoughts?

 

Check the plug and extension cable that is being used on the O2 sensor to extend it to its new location.I might just replace it there could be a bad wire in it or pin. I bet the O2 sensor still works. As a matter of fact just replace that wiring don't even mess with trying to fix it. I bet after you do that everything will work

 

Honda checked out the wiring last week and replaced the O2 sensor again. Today I get in my car and the check engine light is on again. I called them and they said if it's the same sensor again, my only option is to replace the header with a honda manifold ($900). They said that the dc header could be worn inside and could be causing the sensor to break or that the positioning could cause it (the dc header positions the sensor where the pipes intersect). I called DC support, and they said their product would not cause the O2 sensor to break. It seems like I'm only gonna get fingerpointing from either place and I'm gonna have to pay $900. Any other ideas on what could cause an O2 sensor to keep breaking?

 

So you drove from 50 to 101k miles and it didnt break, right? When you took a look at the 02 senor, is it actually broken? Is it clogged, black or dirty looking? Or this is just what you're being told. Also i have ordered dcs 4-2-1 headers and will be putting them on my 93 civic dx hatch i will tell you if anything goes wrong. Has ur gas mileage gone down since you added on all the parts or since ur service lights came on?

I also have a cold air intake and may be getting catback.