Garmin HRM Pro Plus strong offensive odor emanating from the chest strap

Yes! Although I'd say it's a combo of burned electric and cat pee. I started worrying somehow my cat had peed in it except it's always hung on a hook near the top of my bathroom door, so no chance of that. 

Yes! Although I'd describe it as a combo of burned electric and cat pee. I hang mine on a hook near the top of my bathroom door though so no chance my cats got to it. Very bizarre smell.

Consider a sport bag deodorizer product.  The smell from mine was similar to that from my daughter's soccer bag, cleats and shinguards. It's bacterial so washing doesn't usually cut thru it.  

I have washed with a quality natural wash made for sweat and rubbed in some of the deodorizer. Then put in a ziplock and freeze for a day or 2.  The freezer helps to kill the bacteria. 

Best of luck.  This process has worked for me multiple times when the strap became pungent.  Now I'm just struggling with the strap not synching at all. 

Don't you all listen when people tell you that it's not a sweat problem but that it's caused by a chemical smell in the sensors? Putting on deodorant or soap won't change anything

Who says that it's a chemical smell in the sensors? Most people who posted in this thread seem to agree that it's most likely sweat buildup causing oxidisation (for the burnt electronic smell) and/or bacteria development (cat pee or horse smell) depending on strap type and use.

Many people said that washing (not just rinsing) the strap after every use and with some soap - either hand-washing or showering with the strap - helps them reduce or remove the odours.

I wear it into the shower and/or wash it with soap after every single wearing (which is almost every day) and give it a nice soak in vinegar and other things (powdered tide, several other laundry stripper chemicals) every week or so trying new things. None of it has worked so far. Reduce? Sure. But more like from “unwearable” to “don’t try to eat in the room it’s in, and it stinks up anything it touches.” Remove? No. And whatever room I hang it in to dry smells. 

Marcin said:

Who says that it's a chemical smell in the sensors?

I, for one. Had two HRM-Tris, bought new, that smelled bad right out of the (sealed) box. It was not the fabric that smelled, but the rubber sensor pads. That smell got worse over time even without any usage. 

I think all the going back and forth over this topic is that not all of the HRM's apparently have this issue. 

One of my stinky Tris stopped working and was replaced by Garmin. The replacement was, and remained, almost odorless.

It’s not sweat buildup. I’ve thoroughly washed my unit after every use but still the bad smell (like horse/stables) appeared. I contacted Garmin and they sent me a replacement. It’s obvious this is a known issue cause they wouldn’t have sent a new one without any further questions. 

So they changed the policy, and accept a return based upon an odour complaint now? That is good to know. 

At least Garmin Sweden did