bfd811

Just got my car back running again after a month and after putting in my new trans I'm getting "O2 Sensor Circuit No Activity Detected." I haven't looked at it yet but can someone help me understand the meaning of this code. Is it trying to tell me that the O2 sensor is somewhere along the line not getting power from either a broken power or ground wire or is it something that could be internal within the sensor? Either way it sounds like I should get under the car and take a peek at the O2 harness and sensor. and follow it up. Just trying to get an idea of what exactly I'm working with here.

96TransAmboosted

iTrader: (8)

I bet the either forgot to plug it back in or its not fully connected. There is a possibility it's failing but if all was good prior to the work then I'm sure it's just unplugged.

bfd811

I got under the car and checked and it appeared to be connected, I unplugged it and plugged it back in just to make sure the connection was firm. Im tempted just to buy a new one and a real extension harness as I soldered my own up. Could that no activity code mean a failure or do you think its more likely that my harness is garbage? I seam to think that if it failed that I would get one of those high/low circuit codes but im not sure. My pass side o2 was giving me trouble when I first got the motor back in the car, kept blowing my engine sensor fuse, ended up being the sensor itself. I believe these sensors have as many miles on them as the car 197K and I'm sure it didn't help running as rich as I was in my driveway pre-tune with cam/heads. The pass side was dark black when I took it out. I may have possibly killed my d/s sensor now with a rich condition? The car also idles very poorly. It will take a dip to about 550 rpm and start to stumble then pick itself up to around 950 and within 5-10 seconds take another dip down. It will do this until you drive the car, it throws the o2 code and it reverts back to open loop.

96LT1Z

I would definitely say it's time for some new o2s. Get some ac delcos

bfd811

Thats what im thinking. And btw I think we might have the same car lol. Ive got a 96' Z28 black with red badges literally identical to the one in your sig. Ill attach a pic

Spartan7

iTrader: (7)

If you suspect your home-made extension, put a multimeter on it and check continuity. Or just buy one, they're relatively cheap. For O2's, get Denso. If you buy AC Delco, it's just going to be a Denso sensor in their bag, and cost you more.

kris72079

iTrader: (7)

I'd most definitely say that the extension harnesses that you built are not doing you any favors. If you are familiar with wiring at all and the principle that the O2 sensor operates on you'll be familiar with resistance and how it effects voltage and current. One poor solder joint and you'll have failure. The joint may not be visibly poor either. Furthermore, if the O2s are as old as you suspect they may be they are in need of replacement as well even if they were functioning. You have no way of determining accuracy on them so why risk false data by reusing a relatively inexpensive part. To make them appear half as expensive, eliminate the downstream sensors if you haven't already as they only provide feedback to the performance of the cats and are not used to make corrections in the system, merely a monitor. They can be tuned out of the ecm easily.

bfd811

That's what I'm gonna do. Iv'e already had the rears tuned out. Just gonna replace both o2's and harnesses. Should be cheap and should eliminate any problems.

agchoset

iTrader: (1)

Another vote for Denso replacements; I just put in a set of Densos last month and they're working fine.