Codes: P0505, P1508, P0117, and P0118

Car has been idling at 1500 for the past two weeks. On Sunday it threw a code and throttle was very jerky. Pulled the negative terminal and code went away and ran fine. Decided to change the coolant last night. Right before I got to my friends house, it threw a check engine again. His scan tool said P0505. He cleared it and it ran normal. Change the coolant in the whole system and the car ran fine, even on the way home. Drove it today to run some errands and threw a code again. Went to Autozone and these codes were pulled shown at the top.

I've been reseaching, but most threads end with no explanation. I have pulled the wires on the IAC today and engine idle has dropped down to 800rpm. Any help would be appreciated.

 

Probably a vacuum leak, might try cleaning the iacv. If you take intake off and plug throttle body (starve it of air) the engine should die or sputter and almost die, if it doesn't then vacuum leak. other possible causes could be problems with ect and or tps...since you threw p0117/8 I would definitely investigate the ect,

quoted from RonJ@HT (https://honda-tech.com/forums/showth...ghlight=idling)

"And how do I test the ECT?

It's the 2-wire sensor below the distributor. When the engine is fully warmed up, measure resistance across the two sensor terminals. It should read 200-400 Ohms"

hope this helps

 

Sounds to me like a air pocket in the coolant system or you're low on coolant. Low coolant would cause both of your issues. Check your level at the radiator and bleed the system. If you are low check for a leak and repair.