how do i detect vacum leak
A good visual inspection is always the place to start. Have you done a visual inspection? Why do you suspect a vacuum leak? Are you suspicious of one paticular area?
took to auto zone , and when hooked to computer for codes. It threw code for vacum leak.
We always ask “what number code” and this is a perfect example why, there is no code that translates into “vacuum leak” what you have presented is someone’s interpetation of a code.
I do like to guess what code has been interpeted as a vacuum leak PO171, PO174 Fuel trim, System to lean?
It is best to post the actual code if you have it - since, as oldschool notes “vacuum leak” was a half-a@#ed diagnosis rather than what the code said.
Is the van surging/running rough at idle?
If you do want to look for a vacuum leak you can either stick a piece of hose in your ear and fish the other end around under the hood. You should hear hissing if you come across the leak. Use the vacuum diagram located on the underside of your hood. You can also take a torch (propane, butane, whatever), turn on the gas but don’t light - fish that around under the hood. If you hit near a leak the engine should respond.
I’d be surprised to find a vacuum leak on such a new vehicle, but an easy way to search for one is to use a bit of garden hose like a stethascope to listen for a hissing noise while the engine is running. In the case of your van, you’ll have to take off the doghouse inside your van to get to where you need to be to hear a leak. Just watch for the fanblade, etc. Also try moving the lines around gently to find cracked hoses or almost broken fittings
I like to run an unlit propane torch around the places that might have a leak.