I have a civic ex 1999 with about 230k miles in the motor and after a oil change and topping up the coolant the car started to throw the codes P0301,P0302,P0303,p0300 abd p1399 and sometimes the p0505 code with a high idle*about 1.3k*.I changed the IACV, spark plugs and bleed the coolant and its somewhat better but it still throwing the same codes. I suspect it is a vacuum leak but i cant find where exactly. What steps should i take ?

 

How old are the distributor cap, rotor, and plug wires?

P0505 - check for a disconnected vacuum hose.

 

About 4 years i think and ive checked on top of the mani and there is no hoses disconnected

 

Replace them.

What Civic trim and engine?

 

I detected a vacuum leak from the throttle body gasket and my intake manifold gasket by spraying carb spray over these components. You can try and spray certain suspected areas to see if the engine reacts.

 

lol i said the trim on the op but wtv. It's a EX with the d16y8 i believe

 

Will do thanks

 

Sorry, missed it.

Here are the vacuum hoses to check:

 

Fixed it. It was the CC vacuum hose that was disconnected. Good thing i didn't buy anythign expensive lol