Automatic Transmission Plug keeps coming out on 9th generation Honda Civic (2012 - 2015)

The automatic transmission fluid (ATF) plug on my 2014 Honda Civic EX kept coming out even though I inserted it securely. It was a miracle I didn’t lose it while driving. I would be checking the oil and all of a sudden the plug would be out again.
The root cause was that there is a small rubber piece that allows the ATF pressure to be released but it was clogged with dirt. Therefore it kept pushing the ATF plug out.
I cleaned the rubber piece to allow the pressure out and put it back in the two o’clock position (rather than facing forward like it was) to avoid dirt clogging it again. I think it is called Transmission Rubber Breather Cap with part number 21396-P20-000.
Depending on your situation and for how long you had this issue, it is still recommended to replace the plug with an original Honda in addition to cleaning the small rubber piece.
In the video, I measured the diameter of the new one and it was around 20.7 mm. The old one that kept coming out was around 20.2 mm.
These two links are for Honda original parts:
honda.oempartsonline.com/oem-...
honda.oempartsonline.com/oem-...
Check these other Civic videos:
Transmission fluid: • CVT Transmission Fluid...
Coolant Drain and Fill: • Engine Coolant Drain a...
Clean MAF sensor: • Clean Mass Air Flow Se...
Clean MAP sensor: • Clean Manifold Absolut...
Replace PCV valve: • Replace PCV valve on a...
Replace cracked air intake hose: • Replace Cracked Air In...
Clean throttle body: • Clean Throttle Body on...

[@jj963963jj]

I had the plug popping out problem, thank you for the helpful and easy solution.

[@lindafoxwood78]

I bought a 2014 Civic with 190,000 last year for $6000. The guy I bought it from thought the transmission was broken and did not tell me what he thought. He had warmed the engine, so the test run worked great! But when I got it home, and the next day when the engine was cool: I had to run the engine for almost 5 minutes to get the car to move, the trans has seemingly broken. Within a week I found on KZbin that the rubber vent cap for the trans was clogged! I cleaned the vent and put in 1 quart of fluid. A week later, I drained the trans fluid and got 1 1/2 quarts. It is suppost to have over 3 quarts! I drained all the fluid and added 3 1/2 quarts, enough to get the level right to the level plug hole. Runs like a dream for an entire year! Got me great deal on a "Not Broken Transmission" used car. Before all of this, the day I brought the car home, I saw the trans plug hole was missing the stopper. I bought a new one. That week later when I added fluid, I found the stopper - exactly where you found yours: on top of the trans hole area. Wow. I still have both stopped now.

[@gotitdone]

That is a great story! I was smiling while reading it. Knowledge is power right? Check all my other videos for this type of car: MAF, MAP, coolant, PCV, etc. Please consider subscribing to my channel or a $thanks. It will help me on doing more videos like this. I am regularly fixing things around the house and adding videos about it.

[@lindafoxwood78]

@@gotitdone keep up the great job on repairs of the 2014 Civic. I go to work and drive 7 miles a day. My Civic will last 20 more years and will be 30 years old with 250K miles. I can not ask for more from a $6000 car. Thank you for your work on this car.

[@rondail5675]

Amazing! I just changed my 2015 CVT fluid 2 weeks ago and found the fill plug laying on the top of the transmission. My first thought was I didn't replace it during the first fluid change. Now I know it wasn't my fault. Thank you for the video!!!!

[@gotitdone]

I am so glad it helped you. Please consider subscribing to my channel or a $thanks. It will help me on doing more videos like this. I am regularly fixing things around the house and adding videos about it.

[@parkerassociates9864]

Thanks

[@gotitdone]

Welcome

[@markmulder4434]

I cleaned the that cap and noticed the plug had popped out again don't know why it's still popping out may want to keep a check on it

[@gotitdone]

It is still popping out because the plug shrank a little bit already. You will have to replace it. The video shoes the differences in diameter between a used one and a new one. Please consider subscribing to my channel or a $thanks. It will help me on doing more videos like this. I am regularly fixing things around the house and adding videos about it.