2015 Civic SI Spark Plug and O2 Sensor Change

[@nelson32]

FYI.. the Torque settings on that car is 18 N·m (1.8 kgf·m, 13 lbf·ft)

[@Quiet1nside]

Great video. Was really helpful. Delayed this long enough because I knew it would be a PITA. Car is run smooth. Thanks.

[@TheGarnerjustin73]

Damn this was a job, only Honda car ive owned that takes two hours to replace spark plugs. Its not hard but theres just so much to remove to access the plugs. Mine looked just like yours, surprisingly great at 100k miles, any other car and i would have put them back in for another 10-15k miles rechecked them but since you have to remove so much, i just went ahead and threw the new ones in. And if you're wanting better mileage, throw the OEM breather box and intake back on. Those Short ram intakes will cause you to lose power due to it just sucking hot air in from the engine rather than below the front bumper like the OEM breather box does. Open your hood after a drive and just feel how hot it gets under the hood, thats the hot air your engine is sucking in. I can get 38mpg driving easy on my 2012 Si, 35mpg's just regularly driving it and 32mpg's with Spirited driving.

[@Ellron23]

32MPG spirited?! Im 20MPG spirited, 34MPG is the most I've ever gotten that was on a long trip with cruise control. 2015 Si. Just trying to figure out if my spirited is more spirited than your spirited or if somethings off with my car.

[@TheGarnerjustin73]

@@Ellron23 Well you're going to get better mileage not using cruise control and if your vehicle is still stock. But the only time i ever get below 30 mpg's is if im doing strictly stop and go city. On a hot summer day, I can achieve between 42-45 mpg's if i take the car out of gear and let it coast down hills.

[@Ellron23]

@@TheGarnerjustin73 huh, I thought cruise control gave better mpg for long highway trips, I'll have to look into that. Vehicle is stock. What do your accelerations look like, I'm pretty much always romping on it when I can be so I think that's the cause lol. I only break 30 on hour+ long highway drives EDIT: So it looks like cruise control is still recommended for improved MPG on long highway driving. Definitely on flat terrain, maybe acceptable on consistant uphill parts, don't want to use it on rapidly changing terrain.

[@TheGarnerjustin73]

@@Ellron23Yea, im not dogging the shit out of mine or regularly taking it to redline. And ive always felt Cruise Control over accelerates to keep the target speed versus using your foot. These Civic Si's are rated at 38mpg HWY from the factory so you should be getting around that during that normal non spirited driving on highways especially with the economy vtec the K24Z7 uses where only one intake valve is used below 5200rpm. But if you're regularly hitting vtec and taking it to redline, yea thats just going to use a lot of gas.

[@Ellron23]

@@TheGarnerjustin73 I'll try driving with no spirit and see if I can eek out 38mpg highway. The thing is on the highway leg of my drive, I probably am getting 30+MPG, it just averages down against the 15 I get getting to the highway.

[@co_corvetteguy]

Very well done man! Have to do this for my girls civic si and didn’t realize that this was more work than my corvettes plugs! I may pay the dealer now 😂🤣 again very well done thank you!

[@DGuerriero]

A thousand thanks for doing this video...I didn't know all the stuff I had to remove in order to get at the spark plugs. This vid saved me a lot of time figuring-out exactly what had to come out, and in what order. It wasn't very hard, just time-consuming. Good thing I only have to do it every 100,000 miles. One thing: before I started putting all the gingerbread back, I started the engine and ran it for a few seconds to make sure it was okay. One other thing: I wonder why Honda decided they needed three screws in each end of that metal pan - is that their version of your strut bar ;-) ?

[@peterstainer5841]

Jesus Christ, PLEASE PLEASE PLEASE! Place the spark plug in the spark plug socket, attach the extension and use your HANDS to start the thread, so you don't strip out the threads in your block!!!! Please for the love of God, don't jam it in there and wrench down with your wrench!!! PLEASE! *This has been a public service announcement from a good friend and fellow Si owner. Thank you*

[@jackiecarpenter7747]

Good video! Followed along and got mine done. Thanks

[@Modus4]

The plating on NGK plug threads serves as the anti seize. You don’t need that goop. Lol

[@Nazraq04]

At 97k miles on my 2013 Si, I just noticed my MPG drop from 28 down to around 24. Just changed out my canister purge valve solenoid this afternoon. I'm hoping that helps. Spark plugs are next, and I might as well replace the O2 sensor at the same time. It just makes sense to save time and do then together. Especially since I'm near 100k miles.

[@short21yang]

That's good to hear that I'm not the only with dropped MPG. After swapping my O2 sensor still no better MPG so now I'm stuck on what it is. Getting around 24 just like you too.

[@Nazraq04]

@@short21yang Yeah bro, it's kind of a mystery if your car isn't throwing any codes. If you figure out what it is, please come back here and share.

[@brickswisher7672]

@@Nazraq04 clean your maf

[@shaneoparris149]

Change your gas filter

[@Nazraq04]

Replacing the purge valve solenoid fixed my issue completely. Thankfully it was a cheap part and easy to install myself.

[@noereyes82]

Thanks for the vid bro.

[@shednanigan]

@short21yang did you hook it up on a obd2 scanner? Remember what was your code

[@short21yang]

Never got a CEL so that never crossed my mind

[@yandymartinez1720]

Hey I know it’s been a while , I’m experiencing the same problem , did you find the issue by any chance , thanks in advance nice video

[@short21yang]

@@yandymartinez1720 good that people are still this content though it’s been years. I never found out what the issue was. Even after the spark plugs and front O2 sensor my MPG still stayed low (very low 20s). I don’t have the car anymore but what I would recommend next is cleaning the MAF sensor, the bottom O2 sensor, and fuel filter replacement. The car performed perfectly normal no issues just my MPG dropped out of the blue.

[@nelson32]

Thanks for sharing this.. i was wondering how to remove those covers.

[@FlyingGentile]

Wow really easy car to work on.

[@Litto1]

Good stuff but I cringed when I saw the magnet on your fender. I’d be too scared scratching my SI.

[@DIYManiacJohnP]

FYI, NGK coats their threads and suggests not putting antiseize.

[@short21yang]

Been doing this for years and on multiple cars, all with no issues. But thanks for the heads up I didn’t know 😁

[@yurananndos5831]

Awesome video bro, btw what camera were you using?

[@yurananndos5831]

Liked how you explained and showed every steps 👍

[@short21yang]

@@yurananndos5831 Thanks man hope it helped! I'm using my GoPro Hero 7 with a chest mount.

[@terryp007100]

Great DIY sir! One thing about the MPG not improving afterward... if you are going by the display on the dash, and you haven't done the "reset" on it yet, that MPG average is for the life of the car. There's a method for doing the reset so you can start fresh. Just sayin'.

[@theyoungazn]

Did you ever figure out why your gas mileage is down? When you say you used to get 30+ was it on highway or highway/city?

[@short21yang]

I never figured out what caused the MPG to drop because I ended it selling the car off a few months after the making of this video. It was mainly Highway commutes when I was still going to college. Easily getting 30-32mpg hitting about 300-360 miles per tank. Then all of a sudden I started having to gas up more and I would never be able to hit 300 miles on a full tank anymore. That’s when I realized I was getting an average of 23-26 mpg Highway

[@AK-fh1qz]

Is that a K&N cold air intake? Also do you know if having an intake diminishes the performance of the k24 engine over time?

[@short21yang]

Yes sir it’s a K&N, you can check out that video here kzbin.info/www/bejne/pWPQqoOVYpuHq6c. As for diminishing I can’t say Forsure. Bought the car brand new back in 2015 and installed it right after I got the car. Never had issues or CEL come up on it and easy to maintain. But eventually I started having my MPG drop hence the making of this video and changing out my sparks and 02 sensor. I cleaned the MAS too so it Forsure it didn’t cause any issues. I eventually sold my car and got a 4Runner but all I can say from my 6 years of owning my SI with the K&N intake, I would totally recommend it. Not necessarily the intake but any K&N product I would totally recommend. I run their air filters and cabin air filters in all my cars and haven’t been disappointed yet.

[@AK-fh1qz]

@@short21yang I see! I own a civic SI 9th gen as well and I been thinking of adding a cold air intake as well. My car is bone stock and as of now I’m just wanting to maintain proper maintenance schedule for the longetivity of my car. Thanks for the fast response, I’ll consider in the future adding an intake and catback exhaust or something 👍

[@AK-fh1qz]

@@short21yang also do you use a special kind of maintenance table or do you rely on the maintenance minder? I mean before you sold your SI of course.

[@short21yang]

@@AK-fh1qz Power wise, when I first got it I did notice it picked up a little better and it does sound way sexier that's forsure. But as I kept driving it over the years I stopped noticing the power since I was so used to it. The only issue I had with mines was the MPG dropped, I used to get about 32 MPG when I was still communting for college (average 320 miles/tank - max was 366 miles) and all of a sudden it went down to about 23 MPG (average 260 miles/tank). Never got to find out what was wrong with it but I was going to swap out the fuel pump next then I sold it. Not sure if yours has an issue but every once in a while my 1st gear would make a weird noise when my car was at about 50k miles like this video here kzbin.info/www/bejne/eGS4imhjrs6lrKs I was never able to replicate it and Honda either so i never fixed it. Never had a tranny issue either and I drove it from 15 miles new all the way to 122k miles.

[@short21yang]

@@AK-fh1qz As for maintenance I hate taking it to the shop unless I really needed to because I hate waiting for hours for something I can easy do. I did my typical routine every 10k miles which consisted of oil change with Mobile 1 (from Costco), Fram oil filter (never had issues with their products.), tire rotations, clean and reoil the K&N filter with K&N cleaning and red oil product, clean my K&N cabin air filter with K&N cleaning product. Also did my front brakes, bought a few set of new tires, and changed out my tranny fluid every 50k miles following this guy's video (kzbin.info/www/bejne/iKSXn2ZvnNlkl7M). I bought a new set of rear Honda break pads but never used it and it's just sitting up in my storage area but that was going to be next too. Did my spark plugs and O2 in this video here right around 100k as well as drained and refilled my coolant fluid (not a flush). I never really used the maintenance minder, I call that the "Money Light" and I just go off the rule of 1 year or 10k miles which ever comes first for maintenance. I never drove it really hard either, it was mostly for commuting when I was still in college. If I had a house with extra parking, I would never have sold it though. lol Talking to you makes me miss my SI now:(

[@joshcreed6276]

i am regretting buying a 2015 civic si every single time i have to work on it. you have to remove so much extra shit to work on anything on this car

[@emiliodiaz3927]

Man that's a lot of work for a inline 4 spark plugs change 🤓 oh well

[@Rackstoredude]

What size socket for the plugs?

[@SupraRy]

Your spark plugs were not "beat up" at all dude...

[@chasedowney9814]

Mine did that when I switched from amsoil to mobile 1. Went from 32.8 down to 26

[@dkjuan3595]

I’m averaging 25 miles per gallon any recommendation on what I can do to help get more

[@short21yang]

Dam man you were in the same boat as me. Idk why mines dropped either. Was easily hitting 320-350 miles per full tank but I was now getting 250 average and 280 on a full tank if I was really luck. I always drove 80 mph highway when I was getting those good numbers but it dropped out of no where. My O2 change didn’t bring it back up, my next thing I was gonna do was change the fuel pump out, maybe it was starting to get clogged or something. I even tried different types of gas (shell and chevron) but no luck either. I eventually sold the SI so I never got to change the fuel pump.

[@olahautomotive5626]

what camera are you using

[@short21yang]

I used my GoPro Hero 7 with a chest mount.

[@bobfrankfurt9449]

Heat guard was the biggest pain in the ass to put back for me... Not sure why... Gave me PTSD.

[@kenyalonzopineda3219]

where did you buy the stability engine bar How do you search on the internet?

[@short21yang]

Got it off eBay, the brand is called Tanabe and its the front strut bar for the Civic SI. ebay search "Tanabe front strut bar civic si" and it should pop up. Just make sure to get the correct fit for your car.

[@UliSwag]

What did you use to record this video??

[@short21yang]

GoPro Hero 7

[@SmurfSlappa]

Did you check the gap on all of your plugs?

[@dyingangelo]

Installed the similar spark plug no gaping needed

[@short21yang]

I've done man spark plugs changes before on my old car, never gapped before. I buy them from AutoZone and use them straight from the box. Never had any issues before. But you can gap if you like, they sell the tool at AutoZone too.

[@jaredsmith6965]

@@dyingangelo they use iridium spark plugs, no gaping required.

[@outofmind9222]

Doesn’t hurt to check if your plugs need gapping, “measure twice cut once”

[@jr00g25]

Did you replace the coil packs?

[@short21yang]

Nope, don’t have any issues with the OEM ones, still on the original ones since I bought the car 6 years ago so never bothered changing them.

[@creatineaddict]

How long did this all take?

[@short21yang]

depends if you got all the tools it can take a few hours. My wiper got stuck so i had to spray 4d-40 and wait, other than that, if you know what your doing and watch the vid, its fast and can save you a few hundred bucks

[@angelhernandez-ln8ik]

Do i need to disconnect the battery to change spark plugs?

[@short21yang]

i never thought about it, i don't do it ( and in the vid i didn't do it) but i suppose it doesn't hurt. never had an issue with disconnecting on my other cars either but it'll be good safety practice

[@AnythingGoesJoJo]

i thought newer spark plugs do not need anti sieze grease anymore?

[@short21yang]

I've always used it whenever I swap out spark plugs and put some in the boots too and never had any issues. But like I said in the video, its all optional.

[@cosmiccorn5802]

Did you need to gap the spark plugs?

[@short21yang]

nope straight out of the box from AutoZone. Never gapped any of my spark plugs before in the times I've changed them in my other cars either. They all are still running so I'm sure its no biggie.

[@SirDiabz]

Bruh I used to get 38mpg on a pretty consistent basis now I can’t even get past 29mpg lol hopefullly this does the trick

[@ryanlittleton5615]

How much did it cost you in parts?

[@short21yang]

Spark plugs are a little under 10 a piece, the anti seize is a few bucks, both are from autozone. The O2 sensor is OEM from the dealer which was a little under 200.

[@ekbenny3939]

I feel like my car isn’t pulling as hard as it use to (stock) it’s at 95k miles I think it might be time to change these bad boys out

[@eaglesfanchris12]

did your mpg improve after this

[@short21yang]

Christopher Nunes I wish it did. Still getting around 24 mpg after this but before it was up in the the low 30s on the highway.

[@thecountscastle4860]

@@short21yang The problem is most likely the aftermarket air intake . I've seen mpg decrease after people install them. No power increase

[@christianac4253]

whas the part number for the plugs you have?

[@short21yang]

I can't recall, you can search up the AutoZone website or check out CarID for different ones if you like. But I always get NGK

[@JO-fk1bg]

@@short21yang i got the same plugs, which i haven't changed yet. Sitting in my garage changing the oil in my 2015 si. Thinking should i change the plugs but im only at 62,000 miles. Im still getting 32 or 35mpg on a good day(all stock). I do have the b13 service service soon code that just popped up on my dash display. You have a vid on that?

[@fernandovillagomez6382]

Was a bitch honestly but easy job! Just did mine on my ‘12 si and it’s absolutely loving it. Cheers

[@Pokka676]

Did this solved the issue?

[@short21yang]

MPG did not change at all after the O2 replacement.

[@Pokka676]

Didn’t You change O2 sensor and spark plugs at the same time?

[@short21yang]

@@Pokka676 This was all done at the same time. Spark plug replacement since my car hit 120k miles and I swapped the O2 sensor thinking that my MPG might increase. I was easily hitting 30+ MPG or around 320 miles to a full tank but something happened out of the blue and my MPG dropped down to about 23. I was lucky if I can hit 280 miles to a tank. From the forums I've read the cause could have been a bad O2 sensor. Replaced it here in this video and no change. Next I would have changed the other O2 sensor under the car then if that didn't boost my MPG back up, I would have swapped out my fuel filter thinking that maybe it was getting clogged. But I never got to the other two jobs because I sold it and got a 4Runner.

[@mochabear1098]

Any codes after the change?

[@short21yang]

no codes and still bad MPG (

[@clambell9815]

wouldnt recommend greasing/lubing those components lol

[@MistaIntake]

A little dielectric grease on the end of the plug to prevent the coil from sticking to the plug is fine but anti cease on the threads def wouldnt do

[@clambell9815]

@@MistaIntake good to know!