Hello, My name is Bob and I'm new to the forum.

I have a question about where the temperature signal is read for the ECM to go into Closed Loop mode?
Here is the curious thing that happened this morning and I'm a bit confused.
I've been fighting a surging idle after the engine warms up and goes into closed loop. Throwing a P0505 code.
this morning i swapped out a Throttle body with all sensors attached. To save time on troubleshooting and not to make a mess. I did not swap over the coolant lines to the IACV. I left those attach to the old Throttle body and pushed it out of the way. I start the car, idle is fine around 725rpm after warming up and the fans kicking on. I think my problem is fixed. I hook up a live scan tool to get some live data and the car hasn't gone into closed loop mode, even with the temp reading up to 200deg.

I thought the signal would come from one of the 2 normal cooling sys temp sensors. Is there a temp sensor on the throttle body that I'm not aware of?

BTW its an 01 Civic 4dr Auto, D17A2 engine.
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Thanks