Can oxygen sensor go bad from cracked manifold?

[SW20FL]

Hello,

Before I purchased my 97 Civic DX 5spd, the previous owner replaced the number one oxygen sensor. I have a cracked manifold, and my car has been running on the rich side for about a year (29-31 mpg) avg-Failed smog.

I am replacing the manifold/cat, but I am wondering if the oxygen sensor that is only about 2 years old can be bad too? Or if it is just carbon fouled and I can get away with cleaning it off.

Thanks guys.

 

[RonJ]

What makes you think there is anything wrong with the primary O2 sensor? The cracked manifold is enough to make the engine run very rich and kill the cat.

 

[SW20FL]

What makes you think there is anything wrong with the primary O2 sensor? The cracked manifold is enough to make the engine run very rich and kill the cat.

I know the sensor is not the reason why I failed smog. I am just wondering if running it rich could have damaged the o2 sensor as well.

 

[RonJ]

I know the sensor is not the reason why I failed smog. I am just wondering if running it rich could have damaged the o2 sensor as well.

I don't think so. No O2 sensor codes, right? Replacing the manifold/cat should clean up the O2 sensor pretty quickly.

 

[ej7civic]

yea th o2 sensor jus tells the computer what kind of air fuel ratio to send the cracked manifold can mess all that up

 

[Szady]

yea th o2 sensor jus tells the computer what kind of air fuel ratio to send the cracked manifold can mess all that up

Where in NY are you?

OP; Its a pretty common thing among y7's for the manifold to crack. Espeically right ontop of the cat, where the primary o2 sensor sits. Just get it replaced as soon as you can, and all willl be good.

 

[SW20FL]

It does throw a code every few months. I just reset it. Sometimes the check engine light goes out by itself. p0420 or something like that. No codes right now. Been a few months now.

 

[RonJ]

P0420 is not an O2 sensor code. It tells you that your cat is dead or that you have an exhaust leak.

 

[XpL0d3r]

P0420 is not an O2 sensor code. It tells you that your cat is dead or that you have an exhaust leak.

I had that code when my cat s**t the bed, lol.

However, I also did have a bad o2 sensor without throwing a CEL. It was very weird..

 

[SW20FL]

P0420 is not an O2 sensor code. It tells you that your cat is dead or that you have an exhaust leak.

Well there is my answer.

One more question,

Just installed the new manifold/ cat, and when I unplugged the o2 sensor wires from the harness, I forgot which one went where. : O

From the harness end, there is a connector that stick out further than the other. I am not sure which one goes where. They both fit in both 02 sensors .

 

[RonJ]

Primary O2 sensor wires in harness connector:
Wht, Grn/Blk, Blk/Wht, Blk/Yel

Secondary O2 sensor wires in harness connector:
Wht/Red, Red/Yel, Blk/Wht, Blk/Yel

 

[SW20FL]

Ron, Thank you so much!

I appreciate all of the help guys! I got a new cat on. Going to go for a nice drive to "Break it in", and going off to smog retest tomorrow.

 

[kdogg]

mine is cracked too..but still pass smog..

 

[guachi]

Mine is cracked also, my car is running very rich as well and it has been like that for about 7 months, yesterday my CEL light came on and im thinking that it could be a bad sensor throwing that CEL on... Anyone has an idea how to retrieve that code and find out what it means without having to take it to a mechanic for a scanner check?

 

[RonJ]

Click the CEL link in my signature.