Favorite "that was too easy" car repairs?

Gearheads all have run into car problem dilemmas that have drove us nuts trying to figure out. Many end up being topics on car forums including this one on a daily basis.
But sometimes planets align and something that seems like it will be a pain, or expensive, or both, ends up getting resolved easily.
My beater is a '14 Dart I've owned since new and has treated me well, though in the last few years has started developing electrical glitches. Last week I went to check a different information screen on the instrument panel, and when I tried the steering wheel mounted switch to toggle screens, the screen wouldn't change. I had the average MPG screen up, and all my fighting with the switch would accomplish was to 0 out the MPG calculations. I need the screens to work as one of them is the oil life remaining screen, and another is the tire pressure monitor, which comes into play often in cold months because that car's little low profile tires seem to lose about 5 psi for every 20 degrees colder it gets outside!
It looked like I was going to need a new switch module on the left side of the steering wheel, which I found for only around $65 online, not too bad. Then I searched YouTube on their installation, and found it involves removing the airbag first. Hard stop there, I am not comfortable playing with airbags!
So I'm going to need to find a shop, make a schedule, and pay whatever to replace that damn module! My village bought out the trusted garage within walking distance of my house last year to tear down and make a green space, adding another complication in that I need to find a new shop to use.
Over the weekend I had an idea I'd try spraying the switch with a can of contact cleaner I had sitting around. Everything on the switch module looks fairly sealed up, so I had doubts any of the cleaner would seep into anywhere relevant, let alone what were the odds that it was just a dirty contact as opposed to the switch being bad? But why not try anyway, can't hurt. I gave it a good spritz, then sprayed it a little more. Headed out an hour later to drive the car, and I tried to toggle screens with the switch right after I started up the car, and it works like new!
Too easy....
Now if I could only find an equally easy fix for that car's damn trunk lid popping open by itself often when the car is sitting!
What are some car problems that looked time consuming and expensive to resolve that you were fortunate enough to figure out a way to fix quick and cheap instead?

I thought the seals in my torqueflite were probably shot, after two decades of little use, and I had a small puddle under the car after it sat for any time. Had it on the lift last week after a muffler came loose on the trip to Carlisle. Turned out the outside of the transmission was dry as a bone. Speedometer cable cover was the source of the leak. I'm not going to bother with it. Shop fixed the exhaust leak with a stainless steel sleeve and an extra clamp, didn't have to replace a date coded Hemi muffler or a custom bent stainless pipe.

A month earlier, I finally got my coolant temperature gauge to give me a normal reading, after a fellow member here sold me a few used OEM sensors for $20. This car has been good to me.

66 Belvedere no start condition but everything lit up. Suspected the starter relay and it was. This happened during a hard rain...no mat/carpet in the car. Turned the key on and slammed the floor and it fired up. The relay needed a little vibration to help it make up it's mind. Not the 1st 66 to do the same crap. The relay was good to go for months until it wasn't and rinse repeat.

Plenty of times the fix was easy or at least easier than thought. Nice as it sort of balances out those times when it wasn’t. A more recent hassle was one of the indicator lights on a light bar in my modified console burned out. Well, getting to the housing is a supreme bitch, but figured it just needed a new bulb. They were likely the originals in the console from a late 70’s car. When I got the housing out, noticed some heat damage. It had burned out during a car cruise where we were locked up in traffic jams for 45-minutes with my foot on the brake. Those old bulbs get hot. When I inserted a new bulb, it wouldn’t work. Put in another just in case, and didn’t work. The remedy I then figured would be trying to rewire the housing to an unused light. Not something I was looking forward to plus its location wasn’t my preference.

Somehow got the idea of getting LED bulbs. Put one in that non-working socket and it lit up perfect. Replaced the others with LED bulbs and all good. They can stay lit and never get hot. A hassle to do this job, but tons less with those LEDs.

My 2001 Ram 2500 wouldn't go into 4x4. I could have used it at a gig, but managed ok without it. Had driven through pressure-washer rain to the gig, figured maybe something got wet. Tried again a few days later...nope. Figured I'd add it to the list. It's got 284k miles on it - there's always a list!

Coming home from another gig, it was cold at night (and I was drenched in sweat), so I actually wanted some heat. HVAC wouldn't switch from defrost to panel...or at all. Fan worked, but that was the only control I had.

Thought to myself "well....the HVAC runs off vacuum. Diesels don't generate engine vacuum...there's a vacuum PUMP. And...part of the 4x4 engagement is vacuum activated...."

Got home and traced the hose out of the vacuum pump along the valve cover to the firewall...where it had popped out of the rubber boot that connects it to the rest of the vehicle. Stuck it in, zip tie around the boot to hold it ...both problems solved.

Gotta admit, pulling this corolla motor was just too easy.

Never lol

the time I learned what happens when an ignition condenser fails..... swore in was crap in one of my carbs

when it happened to a friend of mine, I looked like a genius

My 440 installed itself lol, I was dropping it in, trans was in the car with a jack under it, working by myself.
Engine on the cherry picker, I could not get the engine to sit down on the mounts and hit the trans locate dowels all at the same time.
The whole damn thing was 1/4" away, contact here and there.
I said heck with it time for a break and went in for dinner.
Came out 45 min. Later and it was all sitting in place, cherry picker had leaked down a bit.