HOW TO FIX the P0300 Check Engine Light on a C7 Corvette!

[@HorsePowerObsessed]

I will be fully testing this fix later this week but it looks promising so far! Seems to have been just a spark plug issue! 🙏

[@FrontSeatDriver]

Car looking great as always!!

[@HorsePowerObsessed]

Thanks, Jason!

[@FrontSeatDriver]

Love that Huracan in the background! ❤

[@HorsePowerObsessed]

Right?! Exact spec I'd order!

[@10SecondZ06]

Sweet. Hopefully it’s all fixed and you can verify after the weather gets better and you can get some seat time. Should feel faster too. First rip on fresh plugs always feels nice.

[@HorsePowerObsessed]

That's the plan!

[@stuartsherman5975]

I feel your pain. You are definitely right. There is not much access in the engine bay to change the spark plugs. I'm glad I'm not the only one that scrapes my knuckles. I'm crossing my fingers you solved the issue. Keep up the great videos.

[@MotorboatToo]

Looking at those spark plugs.... there definitely seems to be some tuning issues going on. The new plugs may just be a Band-Aid fix for now. You may want to dig into why 4 plugs are sooted up and the other 4 are tan(ish). Maybe check the o2 sensor data for fueling issues to help as well.

[@DadsGarageDIY]

That’s in interesting one. Hope that got it.

[@HorsePowerObsessed]

Thanks. I hope so too! Now I just need it to stop snowing/raining to check it out.

[@amber_lynn08]

I’m so glad she is fixed!! 💗

[@HorsePowerObsessed]

Me too!!

[@BillSharp-rm5gx]

Very informative video Justin Thank you for taking the time to share 👍

[@HorsePowerObsessed]

Thank you!!

[@legod1717]

Great video! Glad you got the issue fixed. Crazy how hard it is to reach those plugs! 👍😎

[@HorsePowerObsessed]

Thanks! It definitely was not designed to be easy lol

[@bolivar4537]

Excellent video! Thank you!

[@greatwhitenorthcorvette8133]

You have more patience than me! Great job

[@HorsePowerObsessed]

I went into it trying to have fun.

[@seanmarietta9059]

I’m glad the new plugs seem to have fixed the problem. Is there an upgrade in plugs that you could’ve used? I have seen plugs advertised that produce better sparks than the manufactured plugs.

[@HorsePowerObsessed]

I looked briefly into it and for the most part the answer is no. If you want to go with a colder plug setup for tuned vehicles there are better plugs out there but these seem to be the best for this engine setup.

[@ThePPFGuy]

Such great work

[@HorsePowerObsessed]

lol right?!

[@davebest6369]

Very good vid Justin, great step by step. Hope that solved your code issue.

[@HorsePowerObsessed]

I’ll know for sure tomorrow!!

[@drewpackard6646]

Thanks for information Justin,,great vlog sir!!👍🏽

[@HorsePowerObsessed]

Thank you!!

[@JonathanHernandez_13]

I have a knock sensor and o2 sensors causing a check engine light. I do have long tube headers on my z06 but what do you think I could do to fix it?

[@HorsePowerObsessed]

Do you have a tune on your z06?

[@JonathanHernandez_13]

@HorsePowerObsessed To be honest when I bought the z06 it had the header installed already so I am not sure if it has a tune or not. But I'm assuming that's what it is that it's missing a tune

[@kcintxc]

​@HorsePowerObsessed hey Justin how's it going brother you still own the c7zR-1 I hope anyway that one you don't trade or sell . We have spoke before but my question is once the snow was gone and you had an opportunity to test drive her , did the plugs resolve the issue ?

[@HorsePowerObsessed]

@kcintxc I do still have it and I actually just brought it home yesterday from storage. Drives like a dream, the plugs were definitely the issue.

[@markkutsy]

Gotta love the first choice in replacing turns out to be the right one…Congrats!

[@HorsePowerObsessed]

I definitely felt good about it lol

[@FreeSmokeEA]

What’s up man I have a C7 corvette drove it for 30k miles no problems now at 90k miles it has a misfire type problem CEL was flashing service stabilitrak and rear axle service came on. I changed all the spark plugs and wires and now it doesn’t show the CEL or other lights but starts very slow like doesn’t want to start and when it cranks has a very low rpm and idle is very choppy can you give me a hint what you think it might be. I try to do all the work on my car please help 🙏

[@HorsePowerObsessed]

Sounds like it could be a battery or an alternator issue. Did you replace the battery yet?

[@FreeSmokeEA]

@@HorsePowerObsessed The battery is new just put it in maybe 2 months ago but the alternator has never been changed I’ll try that and let you know thank you a lot. Also when I changed the spark plugs just one of them was dark black with a kind of tar on it don’t know if that means anything but wanted to let you know

[@artbaer3122]

OMG, what a pain to change plugs. And I used to complain about changing plugs on my 65 327/365! I hope the new plugs fix the issue. Thanks for the video.

[@HorsePowerObsessed]

I appreciate the support!

[@tlschmidt71]

How many miles were on them spark plugs? I once changed the single spark plug on my riding mower. I was purdy proud of myself!

[@HorsePowerObsessed]

16k on these ones. That's still impressive! Always good to know how to do these kind of jobs no matter how big or small.

[@ApriliaRSV4Guy]

So if the stock plugs doesn’t last long, is there any aftermarket plugs that will last longer or that’s just how it is on the LT motor?

[@HorsePowerObsessed]

The plugs looked OK so I’m assuming one of them just went bad. From what I can tell there is not another plug that would be better than this one but again it’s unlikely this would happen again or at least that’s what I’ve heard.

[@stephenr115]

Congratulations 🎉 did I miss what plugs you replaced?

[@HorsePowerObsessed]

All of them!

[@stephenr115]

@@HorsePowerObsessed brand name I meant. Did you upgrade or use OEM?

[@HorsePowerObsessed]

@stephenr115 I stuck with oem.

[@LuisFlores-xw1zt]

Thank you

[@HorsePowerObsessed]

You're very welcome!

[@jayjones3254]

You state that there is a bulletin about the stock plugs having issues, but still used the stock ones. Just curious maybe inquiring with the pros at LMR what they use? And or what they recommend?

[@javontedelvon00]

FIRST OFF I LOVE THE CHANNEL! I HAVE A 2016 STINGRAY 3LT Z51 WITH 4200 GARBAGE KEPT! HASN'T BEEN DRIVEN SINCE 2020. JUST PUT IN MY 7TH BATTERY. NOW I HAVE A PO3O8 CODE MISFIRE AND SERVICE STABILTRAK LIGHT ON NOW. THE CAR IS STILL BRAND NEW IN AND OUT. STILL SMELLS BRAND NEW. MATS NEVER USED. SO THE CAR IS BABIED! I PUT 93 SHELL IN IT AND CHEVRON GAS TREATMENT AND IT STILL WONT GO OFF. MY CHECK ENGINE LIGHT IS BLINKING. SOMEONE TOLD ME I NEED TO DRIVE IT TO BLOW IT OUT AND THE LIGHT WILL MOST LIKELY GO OFF SINCE THE CAR IS STILL LIKE NEW. CAN YOU HELP? WHAT DO YOU THINK??? THANKS

[@HorsePowerObsessed]

Thank you! Sometimes all these cars need is a hard drive to help clean out built up carbon but other times, like this situation here in the video, the spark plug itself is actually bad and needs replaced.

[@Vetteman372]

You know, if somebody's starting it up just to move it some other. places in the shop and you keep doing that over and over without running it on the road, your plugs are going to be fouled. just like they are now.

[@whitez06king]

hopefully fixed! i know they are supposed to come pre gapped but i still check mine ! also you got lucky easy to break wires with removal tool !

[@HorsePowerObsessed]

I checked mine off camera, they were all dead on.

[@Vetteman372]

You know, if you took a test light with the engine running and poke wire boot to each of the cylinders, the 1 that doesn't do anything is the one that's messed up. So you didn't need to take all the plugs out. The plugs you got are supposed to be 100,000 miles plugs. I've seen them go 200,000.

[@HorsePowerObsessed]

I wasn’t going to replace just one. I’d rather do all of them anyway.

[@PatrickFugate-qk7ev]

Piece of mind..👏🏽👏🏽👏🏽

[@HorsePowerObsessed]

💯

[@drbooo]

It could be the plug gap???

[@HorsePowerObsessed]

The plug gap was checked on the new ones and the old ones. It was within stock recommendations.

[@lagunavette14]

and that's why I would take it to the shop. I don't have the patience. 😎

[@HorsePowerObsessed]

I just can't trust shops to do the work right.

[@anthonypapa8676]

Typically it is the plugs cuz as we all know how the car sucks the oil vapors out of the valley and puts it into the intake. Yes the car has its own dry sump that takes the vapors from the valve covers no modification needed there. Put an oil catch can between the valley and the intake stops the spark plugs and intake from looking black. I've done all that and turn off my DOD it's a sports car I don't need a going into 4 cylinder.

[@kerry_glock]

I th I’m at 5:35 into the Vlog and after seeing what you are up against, plugs that are possibly the problem, that’s what I think they referenced in my previous comment. The guy ran into the spark plugs were the issue of having soot and/or burnt carbon deposits on the plugs. So, very curious to find out what intimately is the issue! I’m at 10:05 (I am slow at typing in comments lol) Onto the difficult side. Looks like the possibility this really SUCKS TO DO & MORE INJURY TO THE HANDS COMING!!! Question: What is lost needing to disconnect the battery? Codes and/or anything else? SO UNLESS YOU’RE JUSTIN AND HAVE WORKED ON CARS FOR YEARS, you need to know what you’re doing, so don’t try this at home!! Leave it to Justin and the other guys that can do this type of work. At least IMO.

[@HorsePowerObsessed]

I literally didn’t lose anything other than I had to put my car back in track mode. All my settings stuck around.

[@Tewthpaste]

*im still trying to fix my 2014 C7 LT1 misfiring. my scanner only give me a generic P0300 code so there was no specific cylinder. i have changed all the spark plug, the spark plug wires, the coil pack and the fuel feed line but it still misfiring and idling rough and chocking like its starving of fuel or something. i have no yet check or change the fuel Injector yet. that might be my next step but as i dont have the software to properly test these things i think i would just get it tow to a proper shop to diagnose and fix the problem. i hope its nothing major like a new cam or piston or maybe a lifter gone bad.*

[@HorsePowerObsessed]

I’ve seen some reports of an injector going bad but there is a good chance with that engine that there’s an issue with the cylinder deactivation set up. How many miles are on it?

[@Tewthpaste]

@@HorsePowerObsessed it has 60K miles on it and it don't have ECO mode. when i bought the car like 3 years ago with 30K miles, the car has already been tune to remove ECO mode and the previous owner have a procharger in it. it has run great but just a couple months ago, i started hearing a rattling/buzzing noise from the engine compartment right behind the firewall and did some research and some say its the fuel feed line but before i even replace the fuel feed line the engine started misfiring. i then proceed to replace the fuel feed line and i dont hear the rattling buzzing no more but now its the engine misfiring that has become a problem. it just suck because it only throw me a general P0300 code and nothing specific to which cylinder or if its the fuel injector/pump.

[@cryptopunk5657]

Really like all your videos. Just seemed to be non necessary. But much love to you my guy. I hope My C8 Z06 isn't that hard to change plugs 😊

[@HorsePowerObsessed]

I appreciate it! It definitely needed done so not sure what you mean by non necessary.. 🤷‍♂️

[@jackdawson3983]

Curious how replacing the spark plugs with the exact same spark plugs removed the check engine light. What is to prevent it from coming on again for the same issue with the same spark plugs?

[@HorsePowerObsessed]

Odds are very good one of the plugs were bad. Most likely the very first when we pulled out.

[@jackdawson3983]

@@HorsePowerObsessed Curious why replace with the same ones, if those went bad.

[@HorsePowerObsessed]

They were the spark plugs with the best ratings so I just stuck with them.

[@RobZelinka]

I would think this error would be covered under warranty. Even if it were not, why not take it to a dealer who is versed in the ZR1? Whatever the case, the video is very informative and helpful. Thanks for sharing

[@HorsePowerObsessed]

I’m very versed. It isn’t covered under powertrain warranty.

[@RobZelinka]

@@HorsePowerObsessed I was not in any way suggesting that you were not versed. Not all Chevy dealers have techs who are certified to work on corvettes, at least that’s been my experience. I am surprised to hear it’s not covered under warranty. I would have expected to be. In any case, I hope it’s resolved for you

[@TheGjergj79]

Isn't the car under warranty?

[@HorsePowerObsessed]

Yes it is, but spark plugs are not covered under the powertrain warranty.

[@joegotz1971]

Similar to the C4’s EVERYTHING is a 1/16th of an inch a pain in the ass.

[@scottbarker9058]

1 question..is urr engine stok????so many owners hav tunes-etc...done...what doo u expect??..i-dunno???i hav a 19 zo6..stok..no problems..with exception of the exhaust...

[@HorsePowerObsessed]

Yup. All stock minus an exhaust from AWE.

[@corvetteforever]

Stok

[@robertjakicic5878]

ZR1 looking great even sitting still, I can just imagine how much money you just saved by performing this job yourself Justin glad your pesky check engine light is off.

[@twoweeledsoto6072]

Mmm. Sounds like some random issue causing a random misfire. I've done my part. Love this car!

[@HorsePowerObsessed]

Lol thanks!!

[@gabeesquivelLethalZR1]

Glad to see Milwaukee being used and not Dewalt.....🤪

[@HorsePowerObsessed]

You know it!

[@jessemarinjr6374]

JUSTIN ,I JUST DO NOT UNDERSTAND AS TO WHY GM COULD BE POSSIBLY INSTALLING DEFECTIVE SPARK PLUGS IN ANY C- 7 CORVETTE ,ESPECIALLY THE ZR1 ???? HOPEFULLY THIS SOLVES YOUR ISSUE ,AND HOPEFULLY THESE PLUGS WILL LAST 100 THOUSAND MILES LIKE THEY ARE SUPPOSED TO LAST ?? KEEP US POSTED . JESSE VIA LAS VEGAS

[@joegotz1971]

If you would like to know how I fixed mine, I traded it for a C8.

[@sirlancair]

You know how I fixed my $100 problem? I threw $100, 000 at it

[@AQSKY]

Some of those plugs look oiled up . Might need a catch can .

[@HorsePowerObsessed]

It was unburned gas due to at least one of the plugs not firing.

[@dbmracing2019]

That’s what I recommended was checking plugs….. my buddy and Z06 C7 and had similar issue Glad it’s fixed Justin!!

[@HorsePowerObsessed]

Same here!! it drives me nuts when I know something is wrong with one of my cars!

[@dbmracing2019]

@@HorsePowerObsessed EXACTLY. Glad she’s back and it’s a GORGEOUS car man. Can’t wait to one day see it in person

[@HorsePowerObsessed]

@dbmracing2019 thanks man. We’ll definitely get together soon!

[@fanatic26]

Im sorry but power tools of any kind on aluminum heads and spark plugs is a terrible idea.

[@LT4POWERED]

You know, EV’s don’t have these problems… 😆

[@HorsePowerObsessed]

🤣🤣🤣