What temp is a cold start

[Jesseyourcalipers]

How long after driving a truck and shutting it off, will turning it back on be considered a cold start? Fixed a trouble and erased a check engine but need to turn on I/M monitors for smog. So hoping to do it as fast as possible. Thinking something like doing the monitors procedure and shutting it off and waiting 3 hours to be able to do another drive cycle procedure.

 

[Rand]

depends on car
if its parked out in the wind 3 hours is do-able for most cars.

 

[Trav]

When the coolant temp reaches 116-120F and less. Over that the engine will go into closed loop.

 

[eljefino]

For Toyota coolant and air temps need to be less than ~12 degrees apart, so 8 hours.

 

[DGXR]

If it's cool and/or windy enough, I can shut off my Tacoma 2.7 (parked outside at full temp) and let it sit for 45 minutes. At that point, the temp gauge is near the bottom mark (still registering residual heat) but the air pump still comes on when restarted. I consider this to be technically a cold start because the air pump comes on. Not sure if this will help you with the I/M monitors.

 

[Silver]

On my commuter, the stuck lifter has a cold start alarm.

 

[ekrampitzjr]

I've always heard 3 hours was usually enough. But it's not hard to understand that could vary on warm days.