LED dont make heat enough to make condensation disappear, works for normal bulbs.

 

Hope it’s alright for me to chime in here, but my 2019 CX-9 with condensation in one rear taillight was just denied for warranty service under the 3/36. As illustrated by the CX-5 service manual and others’ experience, Mazda considers condensation normal and not a warranty item. The dealer seemed surprised by this, but they say it’s not something they see often (who can say if that’s true). Dealer said actual water in the taillight would be different. Just noting this in case it helps someone else doing a google search.

Personally I think it’s crazy Mazda doesn’t do a replacement on these. The part isn’t a big deal ($650 from the dealer, but what’s the real cost to Mazda?) and the labor is only $90 at my dealer. Taken together that’s really small potatoes to make a customer feel like the manufacturer stands behind the product.

 

Out of curiosity does the condensation persist through the day or are we just talking about in the morning when its cooler and its gone by the time you get to work? If there is water sitting in the light all the time its a lot different than just some vapor in the morning which goes away.

 

I haven’t been able to pin down the trend. The car is parked outside so rain and temperature probably play a role, but it seems to happen at random. Only ever on one side, however, which makes me think it’s a basic seal issue with one side. It’s not one side having a different orientation to the sun, which is something Mazda tries to blame, because I use city street parking and so the car is oriented in completely opposite directions and with different tree covering depending on the spot. Only ever one side gets condensation.

 

I had condensation in my rear lights as shown in photo. I think the dealer used high pressure hose to wash new car before they gave it to me and water went in lamp. I switched on lights and drove around in daytime to warm up and water evapourated. Even these high pressiue car washes can force water into lights. Never seen this in 50 years! Just open light and take out bulb, and with hair dryer blow cold air inside lamp to blow out moisture. Seal up bulb holder and pit back in. You might want to put some electriucal tape around seal but don't trap moisture inside.
Lucky it was not front headlamp, as circite board would go and that cost $1300 for one complete headlight kit and that is aftermarket.