Secondary o2 sensor problems!!!!
 

Ok all im sure this topic has been exhausted but i cant find any results to the issue. 98 civic dx with a y8 swap. Vtec has already been wired in and knock and iacv has already been converted. The problem i am running into is my secondary o2 sensor. I looked at the pinout for it,wired it direct to the ecu, but the sensor is not heating up at all. The CEL immediately comes on after the car is started. Also the voltage is pegged at 1.275 volts. Even after the car gets up to temp, it still does not change voltage. I have tried this on 3 different o2 sensors and swapped the ecu out of a ex that had no CEL. The ecu is a p2p obd2a. Is there anyone that has had this problem and fixed it!!! I need to pass emissions!!!

Re: Secondary o2 sensor problems!!!!
 

Does anyone have any info or can lead me in the right direction?

Re: Secondary o2 sensor problems!!!!
 

What engine harness did you use?

Re: Secondary o2 sensor problems!!!!
 

There are 4 wires. Where did you run them to?

Have you checked whether fuse 15 is blown?

Re: Secondary o2 sensor problems!!!!
 

Why didn't you just extend the factory one?

Re: Secondary o2 sensor problems!!!!
 

Its the y8 engine harness and the cabin harness is factory dx. I ran one heater wire to pin A5 (secondary heater control), the other heater wire to open slot in fuse panel(12v), black signal wire to d14, and ground to d13. I followed the pinout from http://technet.ff-squad.com/wiring.obd2a.htm. I wouldve extended the factory one but they arent on a factory d16y8 engine harness(ex). The y8's secondary is wired into the cabin harness and extends thru the floor. I have the dx trim and the two o2 sensors are wired into the engine harness. Ive tested the sensor with a multimeter and everything is in perfect order. I have even hooked it straight to battery to test the heater and it warms up. But if its hooked to the ecu it wont warm up.

Re: Secondary o2 sensor problems!!!!
 

Which one? Post a picture.

Re: Secondary o2 sensor problems!!!!
 

Sensor side of connector:

Both heater wires are black.

The sensor input wire is Wht.

The sensor ground wire is Lt Grn.

Re: Secondary o2 sensor problems!!!!
 

Ok i was a little confused because you said you converted the IACV, the EX harness (unless you used an auto harness) doesn't need converting.

Re: Secondary o2 sensor problems!!!!
 

On my o2 sensor both heaters are white, signal is black, and ground is greyy

Re: Secondary o2 sensor problems!!!!
 

I tried hooking it up the same way as in the picture and same result. Will post a pic in a couple minutes

Re: Secondary o2 sensor problems!!!!
 

Its not letting me post a pic. Its above fuse 31 or 32. Its a single blade

Re: Secondary o2 sensor problems!!!!
 

Above fuse 32 & 33 is C929 which is Ign. 2 so that should be fine. With the wire colors you listed it would be an aftermarket sensor of some type. Is your sensor a "directect fit" with an OE type plug or universal that has to be wired in?

Have you checked for battery voltage at the sensor with the key on to make sure your connections are sound?

What specific code are you getting?

Re: Secondary o2 sensor problems!!!!
 

Yes it has oe style plug. Yes ive tried the voltage test. P0141

Re: Secondary o2 sensor problems!!!!
 

Or are you talking about the ecu side of the harness?

Re: Secondary o2 sensor problems!!!!
 

Could it be possible my ecu has a bad spot in it?

Re: Secondary o2 sensor problems!!!!
 

Post details of how you did the test and what the reading was.

Re: Secondary o2 sensor problems!!!!
 

Do you have a known good ECU laying around?

Re: Secondary o2 sensor problems!!!!
 

I used my code scanner and watched the live data. The voltage pegs at 1.275 volts and throws a heater circuit malfunction(p0141). The sensor does not warm up at all. I do not have an extra ecu. And the closest one i kno of that i could use is almost 2 hours away

Re: Secondary o2 sensor problems!!!!
 

Get a multimeter and use it to measure voltage at the heater power wire.

Re: Secondary o2 sensor problems!!!!
 

Ok i will pick one up in the morning and try it. I thank you guys in advance for all the help ypu have given me so far

Re: Secondary o2 sensor problems!!!!
 

use the pins location that is in your link you posted and use these to wire up the 2nd oxygen senor thats how I got rid of mine. 96 hatch w b18c(R) swap, just double, triple check all wiring before cutting

Here’s the pin locations:
OBD2a
2nd 02 Sensor ECU Connector
White Wire TO D14 – Sensor Heater 02 Signal (SH02S)
Green Wire TO D11 – Sensor Ground 2 (SG2)
Black Wire TO A5 – Secondary Heater 02 Control (S02HTC)
Black Wire TO A11 – Power Source 1 (1GP1)

Re: Secondary o2 sensor problems!!!!
 

Ok i will try that pinout and post results. Thank you!

Re: Secondary o2 sensor problems!!!!
 

Fixed!!!! I will be posting a tech article with what my buddy did to fix it. Thank you all for the help!!

Re: Secondary o2 sensor problems!!!!
 

So was a thank you for Me