Hello,

I brought my car to a smog shop today, and it looks like there are a few codes that seems to pop up. Some of these codes that comes up are very basic such as O2 sensors and etc. I was planning on changing everything myself, but I ran into a bit of a problem. I open my hood, and I looked down and it seems like I do not even have a plug for my Primary O2 sensor. I do have an O2 sensor connected to the headers, but the wiring was cut off. I tried looking for the plug from the car, but I cannot find it. Even if I went out and bought a new sensor, I would not know where to plug it into.

Could it be hidden somewhere?

Car: 1999 Civic EX, D16Y8. Please see photos below.

1: This is the area where the plug should be, but I cannot find it.




2: This is the O2 sensor I have that is still attached to the headers.


My other issue I have is my a code that came up for the knock sensor (CEL Code: P0325).

I have a wire under my car that isn't plugged in, and I was wondering if anyone can tell me if this wire is for the knock sensor. If not, please let me know where it is supposed to be plugged into.

3: This is a picture from under my car, the wire is right next to the oil filter. I was unable to locate the knock sensor, so if anyone can assist me in locating it as well would be great.


Thank you all in advance!!

 

Looks like you have an aftermarket header with the incorrect 02 sensor. Do you happen to have another 02 right before the catalytic converter? If not you'll have to find the wiring and wire it back to your ECU. For the knock sensor does that connector you are showing have one wire and is it red with a blue stripe? It's possible the previous owner broke off the knock sensor. Should be the blue one in this pic

 

search for the knock sensor may need to get under the car with a flash light. agree with hondapartshero looks like aftermarket header and the po took off one of the plugs for the 2nd o2

 

I do have an O2 sensor right before my CAT. The wire seems to be there. Since I need to pass my smog, I will need to change both upstream and downstream. The O2 sensor right before my CAT should be easy to replace. Can you please verify if the following parts will work with the header I have:

Bosch 13007 or Bosch 13249?

Also, even if I purchase the upstream O2 sensor, where am I suppose to be running the wire to?

@B_Swapped93, what do you mean the previous owner took off one of the plugs?

I went under my car, and it seems like the knock sensor is broken. I cannot directly see it because of the oil filter, but when I feel where it should be, there seems to be a flat surface. Most likely the top part of the sensor where the plug goes into is broken off.

 

Upstream=before cat
Downstream=after/mid cat

Are you throwing a code for the 02?

If you end up having to buy one get a Denso direct fit from rockauto.

For the knock it sounds like they broke it off, you'll have to get a new one if that's the case.

 

Sorry about that. It seems like there is one right before the CAT with a wire plugged into it. The O2 sensor right there is directly under the oil filter. I will need to lift my car up again to see if there is anything after the cat, but the only thing that I saw was the one right next to the CAT.

I am pulling CEL Code:
P0131 (O2 Sensor low Voltage (Bank 1 Sensor 1)
P0141 (O2 Sensor Heater Fault (Bank 1 Sensor 2)

Most likely I will purchase another knock sensor and install that as best as I can. Would you recommend removing the oil filter and working from there?

EDIT:
This is where the one with the current wire still present is: (It is not directly on the CAT, but right before it.) I read the manual and it states this should be the secondary one? While the one on the headers is the Primary?



Image from google.

 

^^ the one in the picture is bank 1 sensor 1. not sure why it's labeled differently.

older cars had the primary up front, which the generic header you have has a hole for. I am going to assume the previous owner just used another o2 sensor to plug the hole instead of just using a bolt.

 

Let me see if I can get this right. When the previous owner installed the headers, he cut the wire from the previous header and used it as a plug on this header? Also, should the upstream O2 sensor (P0131 CEL) be where the picture I posted last is?

I assumed that was the downstream O2 sensor so I did not further search the rest of the exhaust for another O2. I read that the upstream was located on the header so that is why I assumed the one on the pipe before the CAT was the downstream.

Please let me know if the one in the black and white image is the upstream, and I should be looking for another O2 sensor after that, thanks!

 

that is your upstream. upstream is always before the cat.

downstream is after the cat.

 

I will provide update after I get under my car again. I have changed O2 sensor in the past, but this location just seems odd to me. Is this because I have an after market O2 sensor?

 

UPDATE:

I located both the O2 sensor. The secondary O2 sensor was hiding from me behind the CAT. I used my Autel MaxiScan MS3000 to scan for any codes, and it cleared the two O2 sensor issues.

However, when I was scanning with it, I checked to see if my other parts were good.

Under the I/M (Inspection / Maintenance) option, it stated that my CAT, O2S, and EVAP was NOT READY; however, my HO2S was ready.

What would I need to do to repair these issues? I heard of something called drive cycle, would this fix the issue?

And my final concern is that when my O2 sensor came for my upstream (Bosch 13249), the connector is a Male for the O2 sensor and the car connector was also a Male. What I did was splice the old O2 sensor and connected the Female connector to my O2 sensor. It plugs in now, but is there anything I should worry about in the future?

 

The d16z6 and y8 in germany have no knock sensor. Are you sure that your engines in the us have oem knock sensors?

 

i dont think youll be able to clear your o2 code i think it will continue to come back after a bit of driving id find a oem exhaust manifold for smog then you wont get a code. but maybe im wrong i would be interested in seeing how someone would get rid of it on a stock ecu. and your knock sensor should come out by your crank pulley under the timing cover plastic. what ecu do you have?

 

you are mistaken on both parts. he still has the o2 plugged in. and the sensor under the timing cover is not a knock sensor.

 

ya my bad on the knock sensor.

im thread jacking a bit but. my experience with a header the o2 cel will come back overtime after resetting the ecu. is there a way to clear it once and for all or could it be o2 sensor failure?

 

I just replaced the O2 sensor for upstream and downstream and replaced my knock sensor. All codes basically went away; however, I received a new code of P0132. I understand i received this because I spliced a different head onto my O2 sensor. Now I went ahead and bought the correct sensor to fix this issue. I will let you know if the code jumps back up.

Thanks!