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New member here! New Si Owner too.

I am getting the error code P0135 (Sensor heater circuit Bank 1 Sensor 1) in my 2004 Civic Si Automatic (Canada), which is the upstream sensor I'm told.

However, is that an Air Fuel sensor? Or an O2 sensor? I'm asking because I've heard conflicting answers. There is a $150 difference between the two parts.

help...


I want to do the install myself so any tips would be greatly appreciated.

 
Rep Power: 224

Technically both are O2 sensors. The 7th gen Civic uses a narrowband O2 sensor for the primary. When you are searching for a replacement it should specify primary (before the catalytic converter) or secondary (after the cat). Make sure you get the primary. This is ~$100 US from Honda.

Also, highly recommend getting an OEM part. These Civics don't take kindly to cheap aftermarket sensors.

 
Rep Power: 222

04 uses the more expensive a/f sensor for the primary and a normal o2 sensor for the secondary.
I found mine on amazon for around $80 cdn with free shipping, rockauto had it for around $80 but no free shipping.
If you go to the denso website and put in your car's info it will give you the correct part number.
Takes all of 5 mins to change, buy an o2 sensor socket to help with removal and installation.

 
Rep Power: 224

Forgot they switched half way through the 7th gens. Thank you for correcting me

 
Rep Power: 222

All good dude, the only reason I remember is because I had to change mine