Hi,
I am a new member here, stuck in a bind but very determined. I have a 2003 CRV that had thrown a P0134 code after the 02 bank 1 sensor heater failed open. I bought the genuine Honda 234 - 9005 replacement, and have the (from what I've heard) ever popular P0134 no activity code. After checking what I thought would be the obvious ( the connector, fuses, heater circuit voltage at the sensor plug) I still cannot see the signal from the sensor with a scanner. However, I tapped the wires just upstream of the sensor plug, and I see 750mv to 1.2vdc change as I rev the engine. I proceeded to pull the negative battery terminal, the plug connectors at the ECU and begin tracing the wires with a tone generator, then an adjustable DC power supply. I can trace the signal and power from the wide plug connector next to the ECU down to near the accelerator pedal, and back on the other side to the firewall behind the glovebox. What I can't find is where there is a break or opening in the yellow wire with the silver trace markings. I don't know if there is a relay contact, key switch contact, or a broken wire. The ECU seems to be ok, it's just not getting a connection to the yellow wire. Would you possibly have a suggestion or diagram that could help ? I would take it to a service center, but my daughter's CRV has almost 190,000 miles on it, and I didn't want to put a lot of money into it, especially since it is starting to rust out. She only uses it when she is home from college. Any help would be greatly appreciated. Thanks

 

The following is the circuit diagram related to the Air/Fuel Ratio sensor, photo of the location of Connector C101 and Connector C451.

 

Thank you sooo much for the info. I found the relay, put 12vdc to it, checked continuity across the contacts...not good. Replaced with a good relay, now I can see the signal when the loop closes. The signal is very erratic, and the light takes longer to come on, but it still does. It looks like some type of electrical "noise" in the circuit when the alternator kicks in. I couldn't reach it to pull the wires, but I will try that on Friday when my Daughter returns. I also have another brand new Honda sensor on the way that should be here by then. Again, thanks for the help and hopefully I can return the favor by posting how I resolve this...I'm on a mission !

 

Hola Keithg01,

Did you ever found the solution to P0134 on the CRV???