Hello.

So the primary o2 sensor is bad. I actually replaced it with a pretty cheap alternative brand off of rock auto but it still throws code low voltage. I have heard that s2's are pretty picky with the brand of O2. I know Denso is one of the OEM brands. I found one on rock auto, should I go with this?

Thanks in advance.

 

All Hondas are picky about O2 sensors. You should only use Denso or NGK sensors.

But...you may have some other issue.

Did you re-set the light after replacing the sensor? You need to re-set the light (manually turn off the light via scan tool or unplugging the negative terminal on the battery for 30 seconds). It doesn't turn itself off right away.

If you did re-set the light.......did the light come back on right away or did you have to drive for a bit for the light to pop back up?

 

Thanks for the reply man. Yeah, I did reset the light. If I remember correctly it did take quite a while to pop back up. I remember reading that if the O2 sensor is bad somehow, it has to heat up to a certain degree first and then that's when it'll throw the signal, correct? I have looked into a few Denso sensors.

 

Once you re-set the light, the car has to go through a few different drive cycles before it condems or passes the O2 sensor. The ECU has to monitor the O2 signal for a certain set procedure.

You should start with a solid O2 sensor like Denso or NTK. If the light still comes on after that...you may have another problem. The Primary O2 sensor's job is to tell the ECU how much oxygen is in the pre-cat exhaust stream so that it can adjust fuel flow.

Low voltage means high oxygen.
High voltage means low oxygen.

It cycles up and down at something like 47hz IIRC. It's a SINE wave going from 1V to 0V. If the average voltage is lower than expected...the ECU throws a code.

If you have a low voltage code...it might mean that the car is running lean. But it's hard to tell if you have some junk sensor in there.

 

Denso or bosch. The Nermst cell on the cheapy replica ones will often cause bad readouts and the ECU to go haywire (aka throw a code)...