How To Fix P0300 Random Misfire Codes In Your Car




What do you think about this video?

James Zivny: Random misfire can be more involved but you nailed the most common, good video

Bert Esty: mine misfires and has smoke after about 5 minutes of idle.
is it most likely a vacuum issue? compression is good.

Ezekiel White: I have a 99 Mitsubishi gallant 4.2 that misfires what can I check?

Liftmaster 1280: ok, I have a problem, My check engine light is on for a PO300 code. The battery is new, alternator is good, got new spark plugs and wires. What's going on? thanks

travislyonsgary: Thanks Scotty , you really know your stuff and you made it accessible to the lay person.

deepcritik: Pretty basic. But it can be almost anything. Including harnesses, computer, cracked manifold, ICM, blown head gasket etc.

Stephen Dee: I'd recommend adding a check on the distributor for terminal corrosion. Love the Scotty Kilmer Channel. Thanks for putting all these great and super-succinct videos together. They're terrific!

M Balzer: I have a question. my friend has 2002 3.4 Buick rendezvous we took accessory belt off
and the harmonic balancer may have spun without belt on it. do I have to re set timing?

Tammy Hudson: I have a 2012 dodge caravan with the engine light just took it to the mechanic new plugs replaced one ignition coil light came back on again Po300 and pooob. How many ignition coils does it have 6 cyl.?

Paul Wrenfeld: Chevy Malibu 2003 head gasket blown would that cause a po300

ruled by Saturn: Random misfire story.
04 300m
P0300. Random misfire
P0174. Lean condition. Or an attempt to dump more fuel due to lean condition or lack of fuel.
P0420. 02 sensor below threshold. Flashing check engine and stall at low rpm.


The actual problem?
Extremely low fuel pressure. 7psi to be exact.

Check everything when faced with random misfire.
1. Vacuum
2. Spark
3. Timing
4. Fuel.
Those are the basics.
Everything else is a nightmare. Lol.

sami kinnu: Passat 1.8t i have that code + 2 others (missfire in 1&2 sylinders) engine shakes whole car and rpm isnt steady when parked but while driving theres no problem ?

Mr T: I have a 97 Miata thats giving me a p0300 code (random multiple misfires). This code is popping up on my relatively inexpensive Matco MC200 reader... the head and head gasket is new, the timing belt is new, the water pump is new, the thermostat is new, the belts are new, the battery is less than a yr old and tested good, plugs, wires, cap, etc.. are all new as well. I originally got an EGR error code when i took it to the shop (i think they said it was a p0400 code)...i never got that code on my reader, not sure if the code reader i have doesnt read all codes or what (the shop didnt get the p0300 code and i didnt get the p0400 code that they got???), i removed and cleaned the EGR valve but i got p0300 code again. I drove it nearly 150 miles with no CEL then i decided to take it through the higher RPM ranges when shifting and it came on almost immediately once the cars RPM's went over 4000. I have looked at all kinds of common issues from making sure the bolts on the crank pulley are tight to ensure that its not wobbling which will cause a mis-read between the timing wheel and crank sensor, i also checked the gap on the CPS and it is good. I'm not sure what left??? Fuel filter? Fuel pressure reg? I'm lost here. Whgen i drive it i can fell very slight "jerking" when going up thru the gears...its VERY slight, not even really jerking but i couldnt think of a better word.

Ben Dont: im pretty much stumped with my car. 2006 audi 1.8t





17763/P1355 - Cylinder 1 Ignition Circuit: Open Circuit

17766/P1358 - Cylinder 2 Ignition Circuit: Open Circuit

17769/P1361 - Cylinder 3 Ignition Circuit: Open Circuit

17772/P1364 - Cylinder 4 Ignition Circuit: Open Circuit

16684 - Random/Multiple Cylinder Misfire Detected

16686 - Cylinder 2 Misfire Detected




new intake tube/coil packs/spark plugs.
pcv system cleaned/new parts.. i still have these codes. anything else to check?


the car is misfiring with flashing check engine light when 1st started
then it idles normal after a min with a solid check engine light.

i did check the hoses and everything seems to be in good shape.

Jesse Godoy: love this guy, thanks for the good advice 🖒

Charles Roberts: Hey Scotty had a random misfire on my c are and found you info thanks for putting it out there

LEROY HILEMAN: scott, 2002 solara 2.2. code 300, 301 302 303 304 , new spark plugs. one new coil. new fuel filter. sprayed carb cleaner around intake, neg results inspected vacume lines cleaned maf removed maf code, rough idle let engine warm up, hold it at high rpm 3500-4000, short time engine rpm falls off unable to maintain it above 2500., on the road car has a hard time pulling out with power, once rolling feathering the pedal can get it up to 45-50 mph put in neutral car will rev over 4k put back in drive it stumbles.

uruiamnot: Ok, these symptoms say little to me, but to a pro, they are going to give you an idea.
2005 Trailblazer, 4.2L Vortec.
1. I got an exhaust leak that I can hear. It started one day twos months ago and since then, I can hear the engine more like a 1980s truck. Sound is from engine area. I have not located the exhaust leak or know if it's at a gasket or header or what.
2. Random misfires. The code is not confirmed, but I checked it on an OBD scanner and the code was pending P0300. I cleared it, and it came back pending. Cleared it a 2nd time, it hasn't come back.
3. Very rough idle at times... maybe especially when starting it on a hot day.
4. Moderate rough idle most of the time.
5. Rare, but I do see the quick Check Engine Light flash on climbing a hill sometimes.
6. I have replaced 2 or 3 COP modules over the last 2 years as I would find a P030X code and a cylinder's coil went bad. Of course, those situations would start intermittent, then finally set a P0302 code or whatever, and I would immediately replace the #2 coil when that happened.
7. It's never really idled too great, especially summer and with A/C running.
8. I have owned it with 180,000 to 220,000 miles.

I just started it a few minutes ago. No code, moderate rough idle, no check engine light, but I did not drive it far.

Noel Hernandez: I have the random missfire on my 2002 GMC sierra 4.3. I replaced distributor rotor, cap, spark plugs and wires and it still has the issue. is there something I'm missing?

santiago ochoa: you made my year Sir thank you for all this information you are providing, cant thank you enough  a million likes to your video if I could

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