Code 1221

[ahlem]

It was a dark and stormy night, last night, with snow and 14 degrees.
Much salt and sand on the road in Marquette MI.
Today I'm driving and the stuttering starts and the CEL is going on and off without particular regularity.
I stop at a BP station full of snowmobiles and call my son who is near a computer and review stomp code procedures. I have a 1221 code, O2 Sensor. At 65mph at 14 degrees F I would throw a code too.
After I stopped at the station and put in some dry-gas I went on my way for over an hour without further incident. I had a brief recurrence once as I headed south to a balmy 25 degrees without further stuttering.
Any thoughts? The O2 sensor is about 25000 miles old and is a Bosch aftermarket with those grey screw couplers.

[Tiger]

Clean the connections... make sure there is no corrosion and sealed with wire shrink wrap.

[Rick L]

Try unplugging O2 sensor. If it runs better without sensor when warm, you have bad O2 sensor.

[Bill R.]

I have had nothing but trouble with the bosch spliced o2 sensors, i don't use them anymore on any customers cars. Only the ones with the complete harness and i rarely use bosch , the denso ones seem to work much better and last longer

[shogun]

yep, I also do not use universal oxy sensor with the splices, original fit with the wire loom snd the plug is best. Good advice for the Denso, Bill, thanks for that.

[Rustam]

Most likely the problem is with those "grey screw couplers".