P0300: Random/Multiple Cylinder Misfire Detected
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Short trips at moderate speed are usually tolerable; a flashing check engine light means stop - raw fuel is destroying the catalytic converter.
Symptoms
- Rough or shaking idle, especially at stops
- Hesitation or stumble under acceleration
- Flashing check engine light under load
- Reduced fuel economy and sulfur smell from exhaust
Likely causes, most common first
- Worn spark plugs or ignition coils (most common)
- Vacuum leak leaning out the mixture
- Weak fuel pump or clogged injectors
- Low compression in one or more cylinders (worn engine)
- Faulty crankshaft or camshaft position sensor
Read P0300 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0300 means the engine control module sees misfires spread across several cylinders rather than one. The computer watches tiny variations in crankshaft speed; when combustion fails in random cylinders, this code sets. Because the pattern is random, the cause is usually something shared by all cylinders - ignition wear, a vacuum leak, fuel delivery - rather than a single bad part.
Diagnosis order that saves money: read misfire counters per cylinder, inspect plugs first (age and condition tell a story), then check for vacuum leaks with the engine warm, then fuel pressure. Cylinder-specific codes P0301-P0308 point to one cylinder and narrow the hunt to that cylinder's plug, coil or injector.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0300
“Had the software update for piston recall in April 2025, did all the testing and getting codes p0300 all the way to p0305 being that it only has 4 cylinders a 5th cylinder misfire code leads to piston ring failure, it is also burning oil the spark plugs are ashy which I have photo evidence of all of this and they are covered in oil, my car broke down while driving and lost complete engine power I am medically complex. Dealerships are denying the recall as it was "completed" due to a software update. This is a known safety hazard and I could have died. I have all proof it's the spark plugs failing.”2021 Kia Seltos · Sep 2026
“I got the vehicle with 60,000 miles 8,000 miles in vehicle gave me problems gave me a check engine light code p0300 then took it to get inspected then was told it was the fly wheel then it's started knocking vehicle is currently not being droven because of the fly wheel”2022 GMC Sierra 1500 · Aug 2026
“Check engine light on. Codes P0316, P0300, P0301, P0302. Technician confirmed via scope coolant intrusion on cylinder 1 and 2. Technician stated it is known issue with this engine and recommends a new engine for $16,169.92. This has been an ongoing issue for the past two years.”2017 Lincoln MKC · Aug 2026
Show 7 more owner reports
“vehicle may experience driveability issues, which may result in DTCs P0300 (random misfire detected), P0301 (No. 1 cylinder misfire detected), P0302 (No. 2 cylinder misfire detected), P0303 (No. 3 cylinder misfire detected), P0304 (No. 4 cylinder misfire detected), or P0172 (fuel system too rich) or a whirling noise coming from the engine compartment. POSSIBLE CAUSE Based on certain driving patterns and environmental factors, the DTC's stated above may be set or a whirling noise may occur. Apparently only certain vin numbers were affected, mine is not in the list but im still having the exact same issues.”2017 Honda CR-V · Aug 2026
“Misfire on 2 cylinder, noise on start up diagnostic code P0300 P0302 P050 I was driving home and the engine started making a strange sound, vehicle would could no increase speed normally. The dealership did basic analysis from the onboard computer and did a compression test. Heavy knocking sound on passenger side of the engine. The issue happened on Aug 5th 2026. The issue is due to the AFM that causes the lifter to fail and dealership says I need a new engine $15787 or replace cam shaft $14530.”2020 GMC Sierra 1500 · Aug 2026
“Engine started having a rough idle on start up and within a few days the check engine light came on. Took to Lonnie Cobb Ford in Henderson, TN. DTC P0300 and P0302 diagnosed. Coolant leaking on to piston head. Issue involved in lawsuit Miller vs. FordMotor Ecoboost lawsuit. Safety issue due to possible engine lock up or fire. Out of warranty. Quote for $6500 on an $8000 vehicle for an engine defect Ford has been aware of for years.”2016 Ford Edge · Jul 2026
“I experienced rough idle and smell of coolant at start up. Engine light came on. Took car to dealership for diagnosis. Dealer verified my concern ran pcm self test, p0300, p0302 p0303 p0316 present, found coolant intrusion into cylinders. Dealer replaced long block per wsm 303-01. Cost to me $8,036.29. My 2017 Edge had 72,177 miles.”2017 Ford Edge · Jul 2026
“The vehicle in question has the coolant intrusion into cylinders 2 and 3 with rough idle on startup, P0300, P0302, P0303, and white smoke on startup. The vehicle now has 111339 miles on it and the out of pocket cost is more than what the vehicle blue books for in excellent condition. TSB 22-2134 speaks to all the issue and what the repair is. If this is a known issue then I feel this should be a vehicle recall by Ford due to the costly repair.”2017 Ford Fusion · Jul 2026
“I own a 2020 Ford Mustang EcoBoost with approximately 75,000 miles. My vehicle developed a check engine light with diagnostic codes P0300 (random misfire) and P0301 (cylinder 1 misfire). I also began experiencing white smoke from the exhaust during cold starts. An independent repair shop suspects coolant is entering cylinder 1 due to a possible head gasket failure. They have recommended removing the cylinder head to inspect for cracks, check for warping, pressure test the head, inspect the cylinder walls, and replace the head gasket and related components if no further engine damage is found. The vehicle was properly maintained, and these symptoms appeared unexpectedly.”2020 Ford Mustang · Jul 2026
“For a couple months, repeatedly getting various cylinder misfire error codes: P0300, P0301, P0302. The engine stutters on startup and sometimes at idle. Coolant level drops gradually day-to-day. No visible leaks from hoses, radiator, or heater core. Suspect it may be leaking into cylinders. Replaced all four spark plugs, but problem continued to occur a couple days later. Have not yet confirmed with service center where coolant leak is occurring.”2018 Ford Edge · Jul 2026
Cars that report P0300 most often
Based on mentions of this code in NHTSA owner complaints.
P0300 by make
Makes with enough NHTSA reports of P0300 for a page of their own - which models and years report it.
Frequently asked questions
Can I drive with P0300?
Short trips at moderate speed are usually tolerable; a flashing check engine light means stop - raw fuel is destroying the catalytic converter.
How much does it cost to fix P0300?
Typical US repair costs range from $80 for the simplest fix (spark plugs replacement) to $5,000 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0300. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.