1990 Legacy AT. Car has been hard to start in the cold for 8 months. CEL has been on for 2 years. I know I should have done something about it before, but other than hard to start for the last 8 months it ran fine. Car has 180k miles. At first I tried to connect black connector together to read CEL codes but connectors are so close together I could not do it. I did some reading and figured the problem is the coolant temp sensor (the 2 wire one that is for the computer and not the one wire one for the temp gauge)
I forgot to mention that when starting the car cold,at at current temps (30 degrees F) it stalls out and needs to be restarted 2 to 4 times and runs very rough for 5 min. If you give it gas or put it in gear she stalls out. Both fans come on right away and this led me to believe that the sensor thinks coolant is hot. So I changed sensor before I read CEL codes with a used one (100k) and no change. Next day I got some alligator clips and was able to read CEL codes. It coms up 21 water temp sensor, 23 air flow sensor and 24 air control valve. My question is, how likely is it that all 3 of these are bad considering all things, one of them being I already changed temp sensor. I am not really that good with electrical trouble shooting (probably because I've been driving subie's for 25 years and have not had any). Can anyone point me in the right direction. Does anyone know what the resistance of the temp sensor should be so I could at least test it. I have had car for last 14 years and do know it's complete history if that would help. Thanks for reading my long post!