So, Im getting a P0135 error code which means o2 sensor heater circuit sendor 1 bank 1.

It's a new denso 02 sensor that I put on thinking that would fix the error code, but no luck. Even when I reset it with the scan tool, it pops back up the moment I crank the car again. I've even tried leaving the batter disconnected for over an hour. No luck.

I pulled every fuse in the driver cabin box, and every fuse in the engine compartment. All are good.

I checked the connection between the wiring harness from the car, and the o2 sensor plug. Its tight and no loose, frayed, or melted wires.

What else can I try?

 

Pull out a wiring diagram and find out which wire is supposed to get battery voltage to the o2 sensor. Unplug the sensor and turn the key to the on position. Make sure it gets its battery voltage. If it doesn't most likely a fuse is blown. Next, find out which wire is the heater ground. Once you find it check for continuity. That will let you know if you have a good ground or not. If no ground is present look at the wiring diagram to see where the heater circuit gets it ground.


If you don't understand this, take the car to a shop. You will do more harm than good.

 

MM&Y of car would help.

The heated O2 sensor will get it's power from the injector relay in the PGM-FI Main Relay, ground is supplied by the ECU/ECM, most Honda/Acura. 94

 

Thanks, its a 04 accord ex 4 cyl. coupe. MT.

 

Have you checked yet to see if there is power to the O2 sensor, [when ign. switch is in run position?

I do not have a wiring diagram for your 02 Accord, but it is a good bet the power lead is a yellow/black or if powered from a fuse, it should be a black/yellow, either way if you unplug the sensor and test the leads in the plug, [harness side] one of them should be 12V+ when ign. switch is on. 94