Coolant Temp. Sensor 1223 came up

[sschin]

Its been cold around here like 39 degrees and thats pretty cold for bay area... well I started up the car today and it died and then i started it again and it came on fine. I drove it around and then turned it off. 2 hours later I Turned it back on and the idle went back down almost stalling. The car was fine after that and I thought it was just cold. Then I started it again after parking at my friend's and started up fine, the check engine light came on and then the light turned off when I drove away.
I then went home and the check engine light never came on since then.
Anyways I checked if I was getting any codes.
I got 1223.
Coolant temp sensor... well anyways I just had changed my coolant temp sensor a couple months ago, like 4 months ago... What else could be wrong with it? Is the sensor faulty already? Connection dirty? Just too cold at 40 degrees outside... Need help... would this faulty sensor make it so it won't start up correctly?
Please help I don't want to worry about it and blow up the radiator or blow a head gasket from over heating the motor...

1989 325i coupe
5-speed

By the way fan clutch has been changed, water pump, radiator, hoses, thermostat, aux fan resistor, fan belt and the coolant temp sensor.

[DaN]

You can check the sensor's resistance with an ohm meter and compare it to specs for certain temps. If it's out of range replace it.
Look at the conector, is there corrosion? Is the wrong connector plugged into it?

It won't cause your car to overheat, it sends coolant temp info to the computer, so fuel mixture can be adjusted.

Which sensor was replaced? The temp sensor for the gauge? or the one for the ecu?

[sschin]

I changed the ENGINE COOLANT TEMP SENSOR 4 months ago
Should I change the TEMPERATURE SENSOR, WATER?

Today I unpluged the battery to reset and see if it was an old fault code and it cleared and got 1444 (no faults)
A problem happened later in the day where it would start up and go to like 1200rpms then down to 400rpms then dies out. I tryed 3 times to start my car but it refused to start. I got a check engine light again 1223. Everytime this happened it would try and hold the rpms with the gas pedal but it would still die out.

Finally when i got the car on and warmed it up. I would rev it to like 2k rpms and release the gas pedal and it would go down to like 400rpms and then bounce up and down and then settle at normal idle. Everytime I release the gas now it does this.

Is the idle control valve causeing the problems?
The AFM door getting stuck or something?
There also doesn't seem to be any vaccumm leaks from my seeing and hearing.
Once I rev the engine when its on and put my hand in front of the intake i feel it sucking like normal.
I really need some input on this problem.

[Chris E30 Cab]

check the connection to your coolant temp sensor for corrosion....mine was corroded and caused an erratic idle like you're experiencing.

[sschin]

The connection is ok... Not dirty at all.

[jtuner]

Any update on what happened to this car?

[jtuner]

code came up on an 88 325ix ... any help??

[vivalegreg]

yea i know this is an old thread but somebody anybody whats up with this??

my car was having idle problems where it would struggle to start in the am, stall out until it was warm enough then the revs would just keep jumping up and down, it threw a 1223

so we replaced the sensor, and left the battery off, and the car idles fine now, but still has trouble starting and still has the check engine light on with the 1223....

wtf???? now i found out that my trouble startin in the am is possibly my afm, for when i start it with it connected it wont start of if it does it just dies out...if i unplug it it will start right up, but the revs will jump and if i connect right away after having it unplugged and starting it it will just stall out...but if i leave it off for a min, let it warm up, and then plug it in it will kinda bog down but then catch itself at the right idle...check engine light still on and everything,.... ahh what a pain in my ass anyone know what is up with this???

[vivalegreg]

bump bump bump help help help!

[windsor318is]

i have the same thing almost on my m42, except it doesnt stall out, i just wasted 60 bucks on the coolant temp sensor for nothing. anyone know whats the problem?

[Adrian_Visser]

you paid $60 for a coolant temp sensor ? ouch man thats a huge rip off. i paid 30 canadian for mine

have you guys ever considered that the wire may have a break in it from the sensor to the ecu?

i dont know off hand which pin of the ecu connector it is but a wiring diagram would tell you, just test for resistance with a dmm.