Engine And Engine Cooling Problems of Ford Mustang - part 1

While entering an on-ramp and just before merging onto the freeway the vehicle failed to accelerate and I lost complete power from the engine. The vehicle was still powered on, but produced no combustion from the engine. The check engine light illuminated and a message appeared on the dash stating to shift the vehicle into neutral. I pulled off on the shoulder and shifted the vehicle into park. I shut the vehicle off and started it back up. After doing so I had full power once again. This is the sixth time this has happened.

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• what failed & is it available for inspection? air-conditioning system failure. Loss of cabin cooling; dealer recommends compressor replacement (may include related components pending contamination check). Vehicle is at a Ford dealer now; no repairs performed yet. I requested the dealer retain failed parts for inspection. • how was safety put at risk? I live in las vegas; ambient temps ~112°f-120 degrees. This is my primary vehicle for transporting my [xxx] and for my work schedule. With no a/c, cabin temps become dangerously high within minutes, creating a heat-related illness risk (child and driver), impaired concentration, and fatigue during necessary trips. • has the problem been reproduced/confirmed? yes. An independent shop first advised compressor replacement. A Ford dealer subsequently confirmed loss of cooling and produced an a/c repair estimate after diagnosis. • inspected by manufacturer/police/insurance? inspected/diagnosed by an authorized Ford dealer. I opened a Ford customer relationship center case (xxx) and requested goodwill/after-warranty review. No police/insurance inspection. • warning lamps/messages/symptoms & onset? no warning lights. Symptoms began with weak/intermittent cooling in early August 2025 and progressed to no cold air. Mileage at failure ~87,279. A/c clutch cycles but cabin air remains hot. (owner context: original owner, [xxx] vehicle: 2016 Ford Mustang gt 5. 0. ) information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

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I purchased this 2019 Ford Mustang ecoboost 2. 3l brand new in July 2019. It has been well maintained, regularly serviced by the authorized Ford dealer where I purchase the car. It has never been in an accident, and has only 36,100 miles. This vehicle passed inspection last month. The check engine light came on, and then had rough cold starts. I have been informed by the service station that antifreeze is leaking into the engine, and a new engine is required (estimated cost of $11,000). After researching this matter, it appears that there is a design flaw with this vehicle, given the high number of similar occurrences with 2015-2019 Ford ecoboost vehicles. It is my understanding there is even a class action lawsuit related to this issue. Luckily, there was no accident resultant from this engine malfunction in my case, but the NHTSA should investigate this issue, given the high risk it poses to highway safety!.

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On repair order #:[xxx] at lorenzo Ford, the dealership technician documented the following: “verified customer concern, dtc p0304 perform pinpoint test, inconclusive, perform coolant pressure test and found coolant intrusion into cylinder 4. ” this confirms a coolant intrusion defect causing misfire and overheating — exactly the well-documented issue affecting 2. 3l ecoboost engines that is now the subject of a pending class action lawsuit (filed June 2025). Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Check engine light on. Code is p0301 for multiple cylinder misfires. At startup I can hear coolant sloshing around and white exhaust. Coolant is leaking into cylinder 1. The Ford dealer says it needs a new engine. 2019 Ford Mustang ecoboost at 55k miles.

See attached document for complaint.

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The coolant over temperature warning light of my 2016 Ford Mustang ecoboost came on and the engine immediately went on limp mode and I stopped the vehicle and switched off the engine. The vehicle quickly lost power and this created safety concern for other drivers who would have bumped me. I towed the vehicle to the nearest Ford dealership for inspection and they found that coolant went into the engine and the coolant bottle was empty. As a result the dealership has said that the engine engine needs to be replaced…. A big shock for me as I have never had any prior issue with this car which is only 59k illegal on the clock. After further research of my own, this seems to be a common issue with Ford ecoboost engine before year 2020. What surprises me is that there was no other indication or warning before this incident which could have obstructed me to take precautionary action.

Coolant intrusion into the cylinder head. This caused a sudden halt of he vehicle which could have caused an accident and loss of life. The engine coolant overheating temperature warning light came on. Vehicle was inspected by Ford dealership and found to have blown head gasket. The car is vat for inspection.

Since purchasing the vehicle (used) there had been several issues with the engine.

The contact owns a 2018 Ford Mustang. The contact stated that upon starting the vehicle, there was an abnormal knocking sound coming from the engine compartment. Upon inspecting the vehicle, the contact found oil underneath the engine compartment. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was notified of the failure. The failure mileage was 49,000.

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My vehicle experienced a blown head gasket due to a faulty engine block design at 56k miles. The car started running rough for 10 seconds upon a cold start up and was also misfiring. This is due to coolant intrusion through the gasket and it got into cylinder 3 which could have caused catastrophic engine failure or worse. There are several class-action lawsuits against Ford for the defect. Ford has not taken any steps to address this issue with the ecoboost engines on 2015-2019 models. Additionally, Ford did not provide relief to me and I had to pay out of pocket to fix this.

My 2021 Ford Mustang ecoboost is currently experiencing an ongoing issue with the evap purge valve, a critical emissions component. The vehicle suffers from stuttering, rough idle, and a check engine light, especially immediately after refueling, where the engine has stalled multiple times—posing a serious safety risk during traffic re-entry and acceleration. The purge valve has not been replaced, and the issue remains unresolved. I contacted Ford customer relations and three separate Ford dealerships, all of which refused to service the vehicle under warranty, despite the fact that it is still covered under the federal emissions warranty (8 years/80,000 miles) and the powertrain warranty. This refusal contradicts federal warranty guidelines, as the purge valve is clearly part of the evaporative emissions control system. The failure disrupts vapor flow and fuel trim stability, leading to erratic engine behavior and emissions system malfunction. I previously owned another Ford Mustang ecoboost while living in a different part of the state, and that vehicle experienced the exact same purge valve issue, including stalling after refueling and triggering the check engine light. This recurring failure across multiple vehicles suggests a design flaw or supplier defect that Ford has failed to address. There are hundreds of documented complaints and videos online, including on youtube and Mustang forums, showing other owners experiencing the same purge valve failure and warranty denial. This suggests a systemic issue that Ford is aware of but continues to ignore. I believe this issue warrants investigation for warranty non-compliance, emissions system reliability, and potential recall consideration due to the safety and environmental risks involved.

The engine on this 2016 Mustang gt is a 5-liter v-8. The 2015-2017 model years were equipped with plastic valve covers. This is a known defect with these vehicles. The plastic valve covers warp/melt/distort over time, causing motor oil to leak in significant amounts onto the exhaust manifold creating smoke and odor. There is a potential for fire in the engine compartment because of this leak. Ford issued a service bulletin regarding this known defect but has not as yet issued a recall.

The contact owns a 2017 Ford Mustang. The contact stated that after the vehicle was started in the morning, the vehicle was idling rough. The contact stated that later while driving at various speeds, there was a misfire coming from the engine. The contact stated that while checking the engine oil level, the contact became aware that the coolant reservoir level was low. The contact refilled the coolant reservoir however, the engine misfire continued. The contact had taken the vehicle to a local dealer who diagnosed the vehicle and determined that there was coolant intrusion into the cylinders, and that the engine needed to be replaced. The vehicle was not repaired. The contact notified the manufacturer of the failure and was referred by the manufacturer to contact the NHTSA safety hotline to report the failure. The failure mileage was 115,288.

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My engine began experiencing misfires at around 40,000 miles. They were on and off. The check engine light would pop up and go away for around a month. Then the vehicle began having a rough start and check engine light would not go away. I sent the vehicle back to the dealer where they determined that my engine was having misfires due to a coolant leak into cylinder one, stemming from a poor engine design. The engine needed to be replaced. The repair was covered under my warranty.

Coolant intrusion into cylinder/cylinders problem confirmed by a dealer check engine light, cylinder 1 missfire is when I noticed an issue.

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The contact owns a 2018 Ford Mustang. The contact stated that while starting the vehicle, there was a misfire coming from the engine. The contact stated that the vehicle was shaking abnormally, with the check engine warning light illuminated. The vehicle was taken to an independent mechanic, where it was diagnosed and determined that the head gasket had failed, and the engine needed to be replaced. The vehicle was not repaired. The dealer was contacted. The vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 66,637.

1. 2020 Mustang ecoboost is equipped from factory with redesigned block to minimize/eliminate coolant intrusion and or head gasket failure. I still had the dreaded "ecoboom" issue with coolant intrusion on two cylinders as a result of a broken head gasket and poor engine block design. Regular maintenance was perfomed and use primarily top tier 93 octane fuel. 5k mile interval 5w-50 oil changes according to manual using Ford spec oil full synthetic. Cold start misfires and excessive engine shaking are still occurring despite short block replacement by Ford and they won't diagnose properly. 2. Electrical/audio. Issue with crackling audio, audio skipping and both iphones and androids having disconnection issues. Factory reset the sync module twice, attempted reset by unplugging car battery and also checked alternator. Replaced car battery with fresh battery and issue persists. 3. Powertrain: the 10r80 auto transmission is extremely jarring and does not shift smoothly. Hesitates throughout gears, sluggish gears changes. Gives whiplash effect even after a filter and oil change for the transmission with oem fluid and filter. Premature transmission gasket housing failure as well causing atf to leak onto ground.

My vehicle recently had a head gasket leak due to a faulty engine block design. I noticed one day the coolant was lower than it should be but nothing concerning, over a month or so it got progressively lower & the car would also sputter/misfire on startups from time to time. This is due to coolant slipping through the gasket & getting into the cylinder & oil which can lead to catastrophic engine failure or worse. Eventually I got a check engine light & was told it was a misfire after running a diagnostic on the vehicles obd2. I researched what the issue could be &it became more & more apparent that it was a head gasket issue. The oil was contaminated & coolant was getting very low. Apparently it’s a big issue since Ford is now facing a class action over the defect. The vehicle also has some issues with the transmission, for example ill start the car up on a cold California morning 50°f & let it warm up before driving & when I go into reverse after the car will jolt hard as if you were backing up & hitting something like a wall, even in the afternoon when you start it from a cold start & go into reverse it will do it. Not sure why but it’s concerning to say the least. The transmission also feels confused when shifting, when I’m in 4th about to push fit it will get confused & revs will drop slightly before going up again to up shift, also when downshifting due to braking the shifts can feel a bit hard, especially when needing to stopping fast. The engine & transmission are the most importantly parts of a vehicle & without them working properly is something no one should have to face.

The contact owns a 2024 Ford Mustang. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently lost motive power. The contact was able to pull over to the shoulder of the roadway, where the vehicle was able to restart. No warning lights were illuminated. The vehicle was taken to the dealer, who was unable to duplicate the failure. The vehicle was not repaired. The manufacturer was notified of the failure but provided no assistance. The failure mileage was not available.

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2020 and above Mustang ecoboost 2. 3l engines are supposed to have the revised engine block design to mitigate coolant intrusion into cylinders and head gasket leak issues. My 2020 model year Mustang ecoboost with the updated block, is suffering from coolant intrusion into cylinder #1. Confirmed by independent ase certified repair shop as well as Ford dealership. No codes. Symptoms includes cold start misfires and cold start white smoke from exhaust. Mpg was inconsistent as well since the air/fuel ratio is disturbed by coolant intrusion. Car is at roughly 37k miles. If issue is not remedied, your engine may blow up during operation without warning.

5. 0 gt engine continues to lose power and has loud “clicking” when idling. First appeared after may 2025 oil change. Mustang dealer ran codes check - nothing shows up. Mustang dealer has recorded a video / audio of sound and recommends engine replacement. The engine only has 22,000 miles on it .

Check engine light came on. Took car to dealership where I learned that the car needs a new engine due to coolant leaking into the cylinders. I later learned this is a "known issue" with this engine, yet Ford has refused to fix or do a recall. The engine could fail or catch on fire if not replaced.

Took Mustang ecoboost to Ford dealership as result of steady check engine light. Prior to check engine light rough idle at start up that smooths out after 10 to 15 seconds. Dealer identified cyl 3 misfire as well as random misfires. They also observed carbon tracking on plugs. Dealer replaced plugs and performed gdi cleaning service. About three weeks following repair same conditions reappeared rough idle and check engine light. Upon dealer inspection and use of bore scope discovered coolant intrusion in cylinder and recommended long block engine replacement. The second dealer appointment was several days after my warranty expired and mileage was 30,106 miles. Although the dealership was very supportive and understanding Ford would not provide any assistance even after I also pursued relief directly. As a result the long block engine replacement cost is $8,200. After considerable research was able to identify that ecoboost 2. 3 engines as well as other small ecoboost engines all had a block defect that has since been corrected. The defect tends to permit, over time, coolant to leak into cylinders. Although a new head gasket may correct the condition, Ford normally recommends long block engine replacement as a long term fix. This condition if not attended to or if coming on suddenly will cause total engine failure. And, as failure can only occur when operating an engine failure under any driving condition is fraught with danger. To my knowledge Ford has not taken any steps to address this issue with the 2. 3 liter engine built prior to about February 2020. And, at that time made an engineering change to the engine block addressing the design defect. Additionally, Ford did provide relief to owners of other smaller ecoboost engines having a similar design defect. At the present time there are several class actions suits pending for this 2. 3 coolant intrusion issue. One final point should an ecoboost experience cyl or random misfires ensure bore scope is employed.

The contact owns a 2020 Ford Mustang. The contact stated while driving at an undisclosed speed, there were several unknown warning lights illuminated. Additionally, the contact noticed smoke inside the vehicle and there was smoke coming from under the hood. The vehicle was towed to the dealer where it was diagnosed with failed pistons and a blown engine. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was filed. The contact was advised to contact the NHTSA hotline to report the failure. The failure mileage was approximately 73,300.

There is a coolant leak and that has caused significant damage to the engine due to a bad head gasket by poor manufacturing of the engine.

The contact owns a 2017 Ford Mustang. The contact stated that upon starting the vehicle, the check engine warning light was illuminated. The vehicle was taken to auto zone, where the contact was informed that there was misfire in the engine. The vehicle was then taken to the dealer, where it was diagnosed that there was coolant intrusion into cylinder #2. The dealer recommended that the long block be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA hotline for information on NHTSA campaign number: 16v779000 (engine and engine cooling). The failure mileage was approximately 81,000.

For roughly 4mths beginning in April 2025, my 2018 Ford Mustang ecoboost has been suffering from a sporadic misfire, with it the system reporting the misfire and the check engine light coming on, the Ford app identifying the misfire occurring. It was initially repaired with replacing all spark plugs, ignition leads. The sporadic misfire would continue to occur, Ford dealership kept the car for 2 days in late July, took everything apart said they were unable to replicate the misfire, cleared the codes (p0303 being the main one that appears consistently) and said to come back if it occurred again. Roughly 2 weeks later the issue occurred again, took the vehicle back to Ford where they kept the car for 2 days, went through the same process and could not replicate the issue. They dug deeper into the issue and found that the coolant would not hold pressure and with the use of a video scope found that the intake valve had fractured and was leaking coolant into the engine as well as distributing multiple shards and pieces of metal from the valve intake fracture. Informed me that the only option was to replace with a new engine and turboboost. They reviewed and found that there were no recalls related to this issue for this vehicle. After undertaking my own research, I found this to be a known issue for Ford and that roughly 100k vehicles had been recalled starting with the 2020 vehicles for the same issue. The out of pocket expense is around 14k, and the vehicle is currently waiting on a replacement engine to arrive. Currently Ford are not offering any assistance in the cost of the replacement, been though they have been servicing the car since 2020 and it is regularly maintained per their guidelines of vehicle needs based on the mileage driven.

The contact owns a 2018 Ford Mustang. The contact stated while the vehicle was stationary, the contact attempted to warm up the vehicle; however, when the contact returned to the vehicle, the vehicle was off. The contact attempted to restart the vehicle and the check engine warning light illuminated. The contact restarted the vehicle however, the engine sounded like it was losing power with an abnormal ticking sound coming from the engine. The message to “shift to park” was displayed; however, the gear shifter was already in park(p). The vehicle was towed to an independent mechanic, the vehicle was diagnosed with engine failure due to a lack of engine oil. The vehicle was not repaired. The dealer was not made aware of the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 129,000.

Campaign 23e12 under hood liquid fuel jumper line. Gasoline smells inside vehicle and engine stalls to start after refueling. Check engine light.

Head gasket failure from research online there seems to be a flaw in the engine block that leads to coolant leaking in between cylinder walls causing premature head gasket failure.

On April 6th, the ac in the car began stalling and a few days after the engine started making all sorts of noise and failing and ultimately stopped working. I kept the car in my garage until I was able to obtain the money to replace the engine. I just yesterday picked up my car from the shop that replaced the engine (where I paid $13,000). The car is back in the shop and having same stalling issues.

I own a 2018 Ford Mustang ecoboost with a gasoline direct injection (gdi) engine. At around 100,000 miles, the engine developed severe carbon buildup, resulting in cylinder scoring and catastrophic engine failure. Despite following Ford’s recommended maintenance schedule (including a 100,000-mile gdi cleaning service performed by the dealership), my car now has one cylinder with only 70 psi compression (confirmed by borescope and mechanical test). Other cylinders measure 135–160 psi. I have learned Ford is aware of this issue and has made design changes in later models (adding extra fuel pumps/dual injection systems) to address it, but no recall or owner warning has been issued for earlier ecoboost Mustangs. My research and discussions with bg products and independent experts show this is a common flaw with gdi-only systems, and Ford has failed to inform owners or provide a lasting solution. The dealership and Ford have offered limited goodwill, but the engine is beyond repair and requires a full replacement. I believe Ford’s failure to warn owners about this well-known defect constitutes a safety and reliability risk. I am requesting NHTSA to investigate this widespread issue and require Ford to take responsibility for affected vehicles.

Component/system: engine (coolant intrusion into cylinder 1); inspection available: yes; safety risk: sudden power loss on road; reproducibility/confirmation: dealer verified coolant in cylinder 1 after engine inspection; manufacturer, police, insurance representatives or others inspections: no; warnings/symptoms: check engine light turned on, error code p0301, higher than normal engine temperature, low coolant in reservoir, white smoke, rough idle at turning of engine; first appeared: around 100,000 miles.

On 03. 29. 25 (Saturday) the car started rough and the check engine light came on. I took it to the mechanic 03. 31. 25 (Sunday) and they inspected the car and told me that it is either the head gasket or the engine block is cracked because there is coolant intrusion into the cylinders. They asked me to call Ford customer service and ask if there was any way to cover it under warranty as the car only has 64k miles. I was told no, the warranty was 5yrs or 60k whichever came first and the 5 years was October of 2024. They suggested I file a report with the NHTSA. The vehicle right now is at the mechanic as I try to decide what I would like to do with it. If the engine failed when driving, I don't know what would have happened. There were no other symptoms to the problem prior to the failure. In fact, weeks earlier I had it inspected to see if any maintenance was needed and it got a clean bill of health.