Open the windows and fire up all the burners simultaneously. Put a splash of dishwashing liquid in a bowl with water and whip up some foam. Scoop the foam all over, including connections, and look for bubbles. There's yer stinker.

Most jurisdictions offer a service where the local gas provider sends someone to your house for free to detect leaks when there is a gas smell. Give them a call.

Thanks @Joseph — Would you put soap around the burners and on the top itself or just the areas underneath? Also, the cooktop has a single wall oven below it, so tough to check around the regulator area without un-installing the oven. Is un-installing the oven advised in this instance?

@Sharon thanks for this! In NYC they did that. But We are in a suburb — we called our propane provider who installed the cooktop and they said they’ve done all they can; and that if they come out and it’s not the gas line specifically that’s problematic then they will charge us $200 for the service call. I’ve pushed and they won’t budge on that.

"and that if they come out and it’s not the gas line specifically that’s problematic then they will charge us $200 for the service call."

Might be cheaper than blowing up the house. Get someone in to look at it for sure unless you feel comfortable with Joseph's solution.

When you say brand new, do you mean recently installed? If you started smelling gas soon after the install I would say installation was the issue. if you can, do the bubble check on all the connection fittings and you will probably find the leak.

I have seen installers not use any teflon tape or sealant on the pipe fittings.

"Would you put soap around the burners and on the top itself or just the areas underneath?"

I'd do it everywhere I could reach. It'll just be clean.

@jakvis are all fittings meant to have the tape / sealant?

@josephcorlett thank you! I assume we soap everything but avoid the igniter hole. Also won’t the cooktop stop firing if there’s soap atop / sides of the burners.

All the pipe fittings should have sealant. The flare fittings on the corrugated gas connection tube do not need sealant as they seal differently. However you should soap test all gas connections under the cooktop. I have a spray bottle with soapy water that I spray on the fittings looking for an area that is bubbling up.

A few years back we had many issues with defective igniters that had corroded while sitting in storage. Was a quick warrantied fix.

First task would be to check the installation fittings for leaks, typically by the installer/plumber.

Pay what it takes to get this fixed ASAP. Safety first.

The Bosch tech came out. And stated the smell is likely a “By-product of a gas flame”. And said there was nothing they could do (but suggested a second opinion if we still have concerns.)

The issue I’m having is that after 5 min, the entire kitchen stinks. It’s an awful smell that gives me a headache. And to make matters worse, my toddler refuses to go into the kitchen due to the smell. Is a burning smell this intense typical of propane? We had the same appliance / cooktop with natural gas and never smelled anything (and never even used a vent!) And the GE propane cooktop we had in this house prior to this new one never smelled in this way (and we never turned the vent on). Any ideas / thoughts?

I had a new Bosch Benchmark 30" cooktop installed five years ago. The middle burner has leaked a gas smell from the start. The gas company came and detected a gas leak, but NO ONE can find it. We had a hole in a wall to check the pipes--no leak. Bosch says it is NOT their problem. Would NOT replace the cooktop even when it was still under warranty. We had numerous appliance repair companies come to try to repair. The wouldn't open the cooktop, so it was not fixed. I have dealt with this since 2016. Good luck! The sad thing is that I like the cooktop, but the smell is awful and permeates the house. I was extremely disappointed that Bosch would NOT stand behind their product.

@auntrachel — is the smell there (middle burner) during use? Or nonuse? Do the other burners have a smell?

How does an appliance repair service attempt a leak repair without opening up the offending appliance to look for leaks? Weird.

Have you called the company that delivered the propane?