So I have two 1990 volvo 240s - one is my sons... both have developed a single code 123?

ECT sensor signal ...

they are rarely in the same driveway but I was wondering if this condition could be contagious (in case I buy any more 240s)

sorry - really though what's more likely the sensor has failed and is not reporting correct signals or wire break?

AND second question - is it possible that a missing ECT signal could cause a no start condition?

I have recently tore out my intake manifold to fix a failed heater core hose (and a variety of repairs while I was in there) after rebuilding... the car won't start and the ECT 123 code fires right away (rather than the 2 day or so wait until firing that it was doing before the heater hose replacement project).

I'm down to checking the IAC valve connector to make sure it is a solid fit on the plug and I'm considering tearing the intake out again to check for a break in the wire near the ECT sensor.

Since it was running fine with the 123 code before I started the job and now it is starting and revving until I let off of the pedal and it doesn't even try to idle just dies.

what I have confirmed so far...
1 timing order of spark plugs and distributor
2 TPS is plugged in and adjusted for click
3 all vacuum hoses are connected to their various very clean ports on newly cleaned throttle body
4 IAC valve was cleaned with Carb Cleaner when it was out
5 ECT connection was solid the last time I saw it (so deeply buried under the intake manifold now)
6 Knock sensor was never removed or disconnected
7 spark plugs are firing
8 fuel injectors got mixed up but since I believe this is Multi-port injection it shouldn't matter - long wires are attached to farthest two injectors and shorter wires to closest two injectors
9 fuel injector grounds are connected cleanly to clean metal of newly washed intake manifold

sorry for the long post - hope it is thorough and as usual I greatly appreciate any ideas... I'll be checking the IAC connection tonight after I get home.

strackerjack
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Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000