Ford Mustang misfire problems

Filed Oct 21, 2026 · Engine · NJ

My 2019 ford mustang egoboost with only 59,000 miles has a cylinder three coolant intrusion. This is disappointing, as the only right way to fix this according to Ford, is to replace the whole engine. Nobody should expect to have to fix their entire engine. Now on cold starts coolant is leaking in to cylinder three, which is causing misfires and could potentially lead to a safety, risk. Ironically, there’s a lawsuit currently in place for this exact problem. This is a problem, sudden engine failure or stalling due to severe coolant intrusion introduces a dangerous loss of power while operating the vehicle at speed and could lead to a blown or locked up motor. Ford has kept this under wraps since the release of this generation of vehicle.

Filed Oct 20, 2026 · Engine · AR

The engine has a head gasket defect that leaked coolant into the engine causing misfires and requires a very expensive repair for a defect that came with the engine when it was made. Two Ford dealerships have inspected and confirmed the issue. The car threw codes six months ago and we immediately stopped driving it and had the dealership inspect the problem. We have not fixed it yet as the repair is estimated at 6,000. Parts and labor. It is available for inspection. This seems to be a very common issue with this vehicle. We replaced the fuel rail, spark plugs, and have had an independent inspection by a non affiliated repair shop for a similar price.

Filed Oct 13, 2026 · Engine, Transmission · NY

The 2.3L EcoBoost engine failed due to coolant leaking into the combustion chambers. The dealer found coolant present in cylinders 1 and 4, the cylinder 4 piston washed, and vertical scoring on the cylinder 4 wall. The dealer's recommendation is complete engine replacement. Yes, the engine is available for inspection. The vehicle is currently at the Ford dealership and the engine has not yet been replaced. Coolant entering the cylinders causes misfiring and loss of engine power. The vehicle shook on startup and ran roughly, and the misfire was intermittent and unpredictable. A sudden loss of motive power while driving in traffic or at highway speed is a crash risk to me and to other drivers. Coolant loss into the cylinders also reduces the coolant available to cool the engine, creating a risk of overheating. The vehicle is currently not safe to drive. A Ford dealership has reproduced the issue and confirmed it. The technician retrieved stored codes P0304 and P0316, removed the spark plugs and coils, and borescoped the cylinders. A cooling system pressure test was performed and the vehicle was allowed to sit, after which borescope inspection confirmed coolant in cylinders 1 and 4. This was the second visit for the same concern. At the first visit, in August 2026, the dealer replaced all four spark plugs and the cylinder 4 ignition coil, and the misfire returned within weeks. The vehicle has been inspected by an authorized Ford dealership. A goodwill assistance case has been opened with Ford Motor Company and Ford has offered partial coverage of the repair. No police or insurance inspection has occurred. The check engine light illuminated and the vehicle shook on startup and ran roughly. These symptoms first appeared in August 2026 at approximately 32,600 miles. The dealer replaced spark plugs and an ignition coil at that time and the symptoms returned within weeks. Check engine light was not illuminated at the second visit, but codes were stored in memory.

Filed Oct 13, 2026 · Engine · OK

Known engine coolant intrusion problem with the Ford EcoBoost engine. It misfires and was confirmed by a service center that a whole new engine was needed. Car shaking and rumbling-- gas smell. Afraid of it catching fire.

Filed Oct 2, 2026 · Engine · AL

Check engine light came on Sunday night. Monday had AutoZone check the codes - indicated misfire on two cylinders recommended spark plug replacement - Spark plugs purchased with intent to change Tuesday evening- Tuesday morning -Engine overheated on the way to class added more coolant - got the vehicle home and towed to local Ford Dealership the next day to learn that the coolant was leaking into the engine due to head gasket failure. Ford said the engine needed to be replaced.

Filed Sep 28, 2026 · Acceleration, Fuel system · KY

2024 Ford Mustang has shown severe defects since September of 2025. Vehicle has been in and out of shop every month since first incident of vehicle going completely dead without cause or warning. Vehicle has since produced escalating engine misfires, loss of acceleration while driving on highway, and occasional antifreeze seeping through a/c vents on startup. Dash has started to glitch upon startup as well and fuel economy has dropped 7mpg in one month. Every Ford dealership I have went to for repairs, except for Town and Country Ford, has told me, "there's no issue with your vehicle". After a year of issues that are getting worse, and trying to receive answers from my Ford case manager, I went to check on any recalls myself and found there is a recall for my vehicle that has no remedy until December 21st, 2026. Ford case manager did not inform me of any recalls, my Ford app does not display any active recalls, and no dealership has made me aware either. When asked why I didn't receive a letter of notice, Ford Motor Company said, "it got lost in the mail I suppose and we can't send it again". My vehicle is getting increasingly worse and it can not remain in current condition for another 3 months.

Filed Sep 11, 2026 · Engine, Fuel system · TX

I own a 2018 Ford Mustang EcoBoost Premium with the 2.3L EcoBoost engine. The vehicle initially developed a check-engine light and was diagnosed with P0303 (Cylinder 3 misfire), P0316 (startup misfire), and P018C (fuel pressure sensor circuit low). On August 24, 2026, all four spark plugs and one ignition coil were replaced, and a fuel/induction cleaning service was performed. The P018C repair was declined at that time. On September 10, 2026, the vehicle started with an extremely rough idle and produced a very large cloud of white, sweet-smelling exhaust smoke. The check-engine light came on. The original codes, including the misfire codes, were present along with additional codes. The vehicle underwent approximately three hours of diagnostics and road testing. The codes were cleared, and afterward only P018C returned. Testing reportedly did not identify a head-gasket leak, but visible white smoke was still coming from the exhaust when I left the repair facility. Possible coolant intrusion involving the turbocharger was discussed, but the source was not confirmed. Later that day, the vehicle would not crank in Park but started in Neutral. While driving home, the engine began idling so violently at a traffic light that the entire vehicle shook and the tachometer fluctuated significantly. Before September 10, the vehicle had never produced white exhaust smoke, never shaken violently at idle, and always started. The repair facility attempted to inspect the cylinders with a borescope, but both of its borescopes were not functioning. I am concerned about possible coolant intrusion or another engine defect because of the Cylinder 3/startup misfire history, heavy white sweet-smelling exhaust, and severe intermittent rough running. The cause has not yet been confirmed, and I am concerned about possible engine failure or loss of power while driving.

Filed Sep 11, 2026 · Engine · TX

I own a 2018 Ford Mustang EcoBoost Premium with the 2.3L EcoBoost engine. The vehicle initially developed a check-engine light and was diagnosed with P0303 (Cylinder 3 misfire), P0316 (startup misfire), and P018C. On August 24, 2026, all four spark plugs and one ignition coil were replaced and a fuel/induction cleaning was performed. On September 10, the vehicle suddenly started with an extremely rough idle and produced a large cloud of white, sweet-smelling exhaust smoke. The check-engine light illuminated and the previous codes returned along with additional codes. The vehicle continued producing white exhaust smoke after several hours of diagnostic testing. Later that day, the engine shook violently while I was stopped at a traffic light and the tachometer fluctuated significantly. On September 11, the check-engine light returned and the previous diagnostic codes were again present. Firestone documented that coolant was present in the exhaust, that the coolant level was low again after coolant had been added the previous day, that the engine was burning coolant and producing white smoke, and that coolant was mixed with the engine oil. Firestone stated the engine may have a cracked head, failed head gasket, or internal engine crack and recommended complete engine replacement. The engine has now suffered a serious internal failure severe enough that the repair facility recommends replacement. The vehicle has exhibited violent shaking, unstable engine speed, repeated misfires, rapid coolant loss, coolant contamination of the engine oil, and coolant burning through the exhaust. I am concerned that continued operation could result in complete engine failure or sudden loss of engine power while driving, creating a significant safety hazard in traffic. Before September 10, the vehicle had never produced white exhaust smoke or experienced this severe shaking. I am reporting this as a potential safety defect involving the 2.3L EcoBoost engine.

Filed Aug 20, 2026 · Engine, Fuel system · AZ

2020 Ford Mustang with the 2.3L EcoBoost engine. The vehicle has a documented history of coolant loss with no visible external leak, consistent with the known coolant-intrusion defect in Ford's 2.3L EcoBoost engines where coolant leaks internally into the cylinders. The vehicle previously threw a cylinder misfire code (P0301) and now shows a crankshaft/camshaft timing correlation fault (P0017). A scan tool confirmed the exhaust camshaft is approximately 18–19 degrees out of correlation. A new variable valve timing oil control solenoid was installed and did NOT resolve the fault, confirming the problem is mechanical — a worn/stretched timing chain. This wear is consistent with the oil dilution and contamination caused by internal coolant intrusion. The problem has been confirmed by an independent service center via scan data. The vehicle is available for inspection. Warning symptoms included the check engine light, a loud rattle on cold startup, and occasional hard/no-start conditions. This is a safety concern because internal coolant loss can cause overheating, cylinder head cracking, and potential engine failure or fire while driving. Repair cost quoted at approximately $2,000. Mileage approximately 54,400.

Filed Aug 18, 2026 · Engine, Transmission · TX

My 2019 Ford Mustang equipped with the 2.3L EcoBoost engine developed a check-engine light, rough startups, engine misfires/rough running, and some engine knocking. The vehicle had approximately 87,453 miles. I took the vehicle to an authorized Ford dealership for diagnosis. The dealer brought the engine to operating temperature, pressurized the cooling system to 21 PSI, removed the ignition coils and spark plugs, and inspected the cylinders with a borescope. The dealer documented coolant intrusion into cylinder #2 due to a failed cylinder head and recommended replacement of the complete long-block engine due to the extent of the damage. The dealer also documented diagnostic trouble codes P0300 and P0316 for misfires, along with P008A and P018C related to low-side fuel pressure. I am concerned that internal coolant intrusion causing misfires, rough operation and engine knocking could result in significant loss of engine power or engine failure while driving, creating a safety hazard, particularly at highway speeds or in traffic. Ford Customer Relations was notified but declined financial assistance because the vehicle is outside the factory warranty and stated that there is no applicable recall for my vehicle. The vehicle has not been repaired and is available for inspection. The Ford dealership's written diagnostic report and photographs of the cylinder inspection are available.