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View Full Version : Bad Primary O2 Sensor?


Slip_Angle
04-19-2010, 07:40 PM
Just replaced my primary O2 the other day because I got a code (once) and it was starting to get sluggish. It still works but I thought better to replace it now then wait until it's gone.

Anyways, I picked up a new Denso replacement and installed it a few days ago. A/F ratios were good in closed and open loop and everything checked out nice.

Today my A/F and STFT were all over the place and my car was stumbling on return to idle and almost stalling. Seems the new O2 was defective... I switched off closed loop and the car is running fine now. I'm surprised a new O2 would fail this quick but I guess anything is possible...

I'm hoping Amazon will send me a new one but I waited too long to install it and now I'm past the "return date" at Amazon by about 15 days. Hope they believe in good will.
talonXracer
04-19-2010, 08:06 PM
Are you sure it is the A/F sensor and not another problem?
Deadphishy
04-19-2010, 08:16 PM
a short somewhere that took out the first O2 sensor as well?
Slip_Angle
04-19-2010, 08:16 PM
Are you sure it is the A/F sensor and not another problem?

What else could it be?
Slip_Angle
04-19-2010, 08:18 PM
a short somewhere that took out the first O2 sensor as well?

First O2 still works, it's just on the slow side to warm up and like I said it did throw a heater circuit code a couple months ago when it was cloder here..
talonXracer
04-19-2010, 08:29 PM
An issue with the connector?

But it could be a faulty sensor, it wouldnt be the first time! LOL

Just dont want you wasting money on a new sensor and not have it fix the issue.
Slip_Angle
04-20-2010, 05:24 AM
An issue with the connector?

But it could be a faulty sensor, it wouldnt be the first time! LOL

Just dont want you wasting money on a new sensor and not have it fix the issue.

Connector seemed ok but I can check it again. I noticed while data logging yesterday that once I came to a stop and hit idle the stft would start at something ike -20 then creep down to ~ -2 to 0 and settle there. Took a few seconds. If I recall orrectly this was indicitive of a bad sensor.

I'll do more testing though before I do anything.

Thanks for the advise.
Slip_Angle
04-20-2010, 08:57 PM
I spoke with Amazon and they are shipping me a new sensor at no cost and no questions asked. Pretty nice of them considering my 30 day refund time was expired. Car has been running in open loop and running well.
Deadphishy
04-21-2010, 04:03 PM
That is awsome.
Slip_Angle
05-06-2010, 08:18 PM
Swapped the sensor and everything is good again.