Why did my Oktoberfest turn out so light?

I have brewed Oktoberfest / Märzen beers. I also normally follow an all grain recipe and use Ale Yeast, namely; Nottingham and ferment between 16’C - 17’C (60’F - 62’F) relatively cool for an Ale. In my experience there only one way this beer or even ‘a’ beer turns out lighter than expect, and that’s when your OG was too low for the style. I.E your initial sugar density was too low or diluted - with this dilution you also wouldn’t have had the normal steeping flavors that go along with it.

You didn’t give any OG / FG readings that would normally answer this quite conclusively.

Now if yours was All Grain recipe - I’d say your Mashing wasn’t efficient and so extracted/converted too little sugar from the grain.

Now if it was extract / kit then it’s more likely you added more water by accident than you should have and or if you were suppose to boil as part of the recipe you under boiled - again meaning the concentration of sugar was not increased enough.

I’m an quite sure your wort was too diluted and or sugar concentration was to low. E.G for a Märzen you should of had an OG of 1.058 - 1.065 the finished at 1.010 - 1.013. You never said in your question that it was sweet this I expect your terminal gravity was on point but I expect you starting or OG would have been around 1.030 - 1.038.

Just watch your OG next time and make sure it’s on point. If it’s still too low - allow for more boil off.

It sounds like you've done everything correctly - maybe you just had the wrong expectation for the kit?

I looked up the recipe and plugged the ingredients into my beer calculator, and assuming the can of amber extract was 4 lb LME, it should put you right in the middle of the range for an Oktoberfest - 10 SRM, and nice maltiness.

Also, I'm seeing that the kit should come standard with ale yeast - this, of course, won't have the same characteristics as a lager, but I would expect that if the kit were designed as an ale, that the flavor should be good with an ale yeast. It might not hurt to double-check that you used an appropriate strain - something more malty. Last year I brewed a bock with an ale yeast - Wyeast 1007 (German Ale), and it came out surprisingly tasty for an ale yeast in a lager recipe.

The only other thing is that it looks like that recipe might be designed for a really small boil - the instructions say to only add 1 to 1.5 gallons water for the boil. Staying on the lower end of volume will result in more kettle caramelization, which will help with flavor and body, although the trade-off is lower hop utilization, so your beer won't have as much hop bite.

My guess is that if you used a good strain of yeast, then the problem is just that you expected more of the kit than it was capable of delivering.

It undoubtedly had to do with the ingredients in the kit. Is there any way for you to know what was in it? Using an ale yeast instead of a lager yeast will mean it is less clean and crisp than a lager would be.