rileysowner

So I had issues with both O2 sensors on my 05 Civic with a 1.7 D17A2 engine. The upstream sensor had a failed heater, and I thought originally that the downstream one did as well. I needed to replace the cat, and couldn't get the old sensor out, so I figured getting a new one wasn't a big deal and didn't do the whole diagnostic. Sadly, the new sensor didn't get rid of the error, so I started testing things. The sensor has the correct resistance on the heater, so I am pretty sure it is good. The harness plug has power, but when testing the ground, I am not getting any. I have ground for the upstream sensor, and I am guessing that the ground the ECU uses for both of them is shared, so the ECU has good ground. Since I had the engine replaced a couple of years back, and my suspicion is that the wire between the ECU and the sensor is broken, but with a Honda being a car, getting at the wiring unless one has freakeshly small hands, is difficult to impossible. I was wondering what is the wire routing for the downstream O2 heater circuit ground wire is? Are there specific places people would suggest looking? Finally, how difficult is it to get to the wire for the ground at the ECM end so I can do a continuity test from the ECU plug end to the O2 harness plug? Links to how-tos or videos would be much appreciated.

Colin42

What brand are the sensors and where did you get them from?

rileysowner

Denso, from an online parts place, and they are the ones for my engine model. I made the mistake of getting cheap ones before and of not getting ones for the D17A2 engine. The sensors are fine, the issue is the heater, in particular, not getting a ground on the downstream.

gpsnuff

did you get it resolved, i have the same issue, thanks, steve

rileysowner

No, I never did get it figured out. While I was working on it the car developed transmission issues, and we ended up getting rid of it since my wife didn't trust it any longer. I wish I could help.