P1166
 

So I replaced both oxygen sensors. Now I'm getting a p1166 code . any ideas ??

Re: P1166
 

P1166 Air/Fuel Ratio (A/F) Sensor 1 (Sensor 1) Heater system Electrical Problem

Is this on a ULEV Accord?

If so, that code is pointing to a problem with the heater circuit, possibly no voltage getting to the heater. Check the connections and ensure you are getting 12v to the heater.

- Check the ECM/Cruise Control 15 amp fuse in the drivers side dash fuse box
- Also check the passenger side dash fuse box 20 amp LAF Heater fuse

At the sensor plug, the red wire (pin2) and the blue wire (pin1) go to the heater circuit. On the harness side there should be 12V within 80 seconds of engine start.
The corresponding terminals to the heater circuit should show about 10-40 ohms resistance across the heater.

Re: P1166
 

So I took off the upstream sensor and put back the old one. Now there's no code . I may have bought a defective sensor.

Re: P1166
 

That is very possible. I have seen some sensors fail out of the box. What brand sensor did you buy? NGK (NTK) is the OE manufacture for O2 and AF sensors. sometimes even the universal fit NTK can have some issues though. It's always best to buy a plug and play OE replacement if buying a real deal OEM from the dealer is too costly.

Re: P1166
 

I bought a denso from a private party on eBay. Lesson learned