I own a 96 neon and it has a very high idle at times. I've changed the idle motor, o2 sensor, temp sending unit plus plugs, wires, etc... Now I had a CEL come on and it gave me 'lean mixture' and 'vehicle not reached targeted idle speed' I don't know what else to do. I do know that the heater core leakes and needs to be replaced (this weekend), will that give the computer a false reading at the coolant temp sensor and cause it to idle high? I need to fix this problem so I can sell the car. Thanks guys!

-Mattie

 

oh yeah it's a SOHC too

 

Did you change/check the IAT sensor or TPS sensor also?

 

i have not since it doesn't show a code for that, should I still check that? and would a low coolant situation cause it to have a high idle?

-Mattie

 

Low coolant, no. Its probally the IAT sensor.