Mazda MAZDA3 engine problems

ENGINE

Catalytic converter keeps giving me check engine

NHTSA complaint #11706906 — an unverified report by a vehicle owner.

ENGINE

My 2018 Mazda 3 has an intermittent electrical failure on the high-speed CAN network that causes multiple safety-critical systems to fail while driving. When the fault occurs, the dash lights up with warnings for powertrain, ABS/traction, lane departure, collision-avoidance, TPMS, immobilizer, and the check-engine light. The car also hesitates or “lurches” between 15–30 mph during these events. At one point in 2024, the vehicle went into limp mode on the freeway, creating a safety hazard. These failures are intermittent but repeatable. Diagnostic scans from 2023–2025 show multiple U-codes for lost communication between control modules; two later became permanent. The issue appears unrelated to any one component and affects many systems at once. The vehicle has been to every Mazda dealership in the North Texas region (Mesquite, Freeman, Hiley, Norm Reeves, Town North). All performed only basic scans; none completed a full CAN-bus or wiring-harness diagnostic. Town North kept the vehicle for six weeks (Sept–Oct 2025), replaced a coil and spark plugs, performed a camera calibration and a TCM update, but the network failures returned within 38 miles. We sought independent inspection only after dealerships repeatedly refused diagnosis whenever the warning lights were not on at the moment of arrival. In November 2025, a technician found significant internal corrosion inside the negative battery cable; touching the cable reproduced the full failure immediately. The corrosion extends deep into the wire sheathing. This appears to be an electrical defect affecting CAN communication and power/ground integrity. When the fault occurs, multiple safety systems disable at once and the vehicle behaves unpredictably. Mazda Corporate has declined further assistance, and the defect remains unresolved. I am filing this report because this is a recurring safety issue that may affect other vehicles of the same model and year.

NHTSA complaint #11700428 — an unverified report by a vehicle owner.

ENGINE

What component or system failed or malfunctioned, and is it available for inspection upon request? The high-pressure fuel pump failed. This component failure prevents the car from starting or staying running. The check engine code confirmed the high-pressure fuel pump failure. The failed component is currently at the Mazda dealership and is available for inspection upon request. How was your safety or the safety of others put at risk The car suddenly stalled while driving on the roadway, creating a dangerous situation. If this had happened on the freeway or in fast-moving traffic, it could have led to a serious accident. Losing power and control of the vehicle at higher speeds poses a major safety risk to both the driver and surrounding vehicles. I was fortunate that the failure occurred on a city street rather than on the freeway. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. The Mazda dealership inspected the vehicle and confirmed that the high-pressure fuel pump had failed, which was also verified by the check engine code. This failure caused the stalling and starting issues. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives, or others? The vehicle was inspected by an authorized Mazda dealership, which diagnosed and confirmed the high-pressure fuel pump failure. It has not been inspected by police or insurance representatives. Were there any warning lamps, messages, or other symptoms of the problem prior to the failure, and when did they first appear? Before the final failure, the car was hesitant to start, and after it stalled, the check engine light appeared. There were no prior warning messages or signs before the car suddenly stalled while driving. Additional details: The car is only seven years old with approximately 52,000 miles, and it is concerning that such a critical component would fail this early.

NHTSA complaint #11694610 — an unverified report by a vehicle owner.

ENGINE

Odometer Fraud. The contact purchased a 2014 Mazda Mazda3. The contact stated that the vehicle was making an abnormal growling sound. The check engine warning light was illuminated. The contact discovered a mileage discrepancy after the purchase. The vehicle was a private sale. At the time of purchase, the vehicle mileage was 140,000. The vehicle was taken to the local dealer, where it was diagnosed and determined that the motor mounts needed to be replaced. It was later discovered that the Title mileage was 197,687.

NHTSA complaint #11689873 — an unverified report by a vehicle owner.

ENGINE

Spontaneous loss of power while driving on highway. Check engine light came on. Speed limited by car. Continues to vibrate especially at idle from cold start. Code P0304 intermittently popping up.

NHTSA complaint #11656416 — an unverified report by a vehicle owner.

ENGINE

The thermostat malfunctioned on this vehicle, resulting in the thermostat remaining open and providing excess coolant to the engine, which in turn damaged internal components of the engine (compromises safety), decreased fuel economy, increased emissions (compromised safety), and decreased the life of the engine within the vehicle. It is available for inspection upon request. The vehicle has been inspected by an independent mechanic and will be inspected by the Mazda dealership in 7 days. There were no prior warnings until the engine malfunction notice appeared, the vehicle began to make jolts and stuttering sounds, and the temperature gauge within the vehicle failed to rise to optimal range. As this occurred while the vehicle was in use (safety concern), though I was pushing the gas there would be delayed response due to improper temperature, which increased the risk for an accident to occur.

NHTSA complaint #11644041 — an unverified report by a vehicle owner.

ENGINE

The contact owns a 2021 Mazda Mazda3. The contact received notification of an unknown Class Action Lawsuit Number however, the part to do the repair was unavailable. The contact stated that the manufacturer exceeded a reasonable amount of time for the repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.

NHTSA complaint #11631026 — an unverified report by a vehicle owner.

ENGINE

My 2023 Mazda 3 started to have a more terrible and annoying rattle after 3000 miles. The engine will resonate and knock when it reaches a certain speed. The slow speed light throttle acceleration rattles. The most annoying thing is the multiple rattles inside, dash, door panels, and roof. It is like a can in the summer. What’s more terrible is that in the winter, its internal door panels, windows, and dash make a knocking sound like a screw is loose. I went to multiple Mazda dealers and it was obvious that they could not find and fix the issue. They either said they didn’t hear it or said it was a "normal noise". This is disappointing and unacceptable.

NHTSA complaint #11628034 — an unverified report by a vehicle owner.

ENGINE

This began on 10.19.24 and as of 11.03.24 is ongoing and not repaired. On 10/19/24, while I was at a red light, the RPMs on my vehicle went up and down repeatedly. After I arrived at my destination, which was about a half mile away, and put the car in park, the RPMs repeatedly went up and down between 1,000 and 2,000 RPMs and the check engine light came on, and a message displayed saying malfunction - have the vehicle inspected. I spent $100 at my mechanic who could not pinpoint the issue. After I picked up the car, I stopped to get gas and then my battery died. I then decided to take my car to the dealer where I purchased it, Mazda of Roswell. After I put the car in park at the Mazda of Roswell service department, the RPMs started going back and forth between 1,000 and 2,500 RPMs. My car spent 6 days at Mazda of Roswell, where the service dept was unresponsive and my car was never inspected. I then spent $1600 at North Roswell Automotive, only to have the issue appear again after driving less than two miles. I am not sure it is safe to drive a vehicle in which the RPMs are unstable. So far this has only happened when the car is idling or in park. If it happens when the car is in motion I hope I am able to control the vehicle. My car needs service at a Mazda dealer but I need the dealer to be honest with me about what to expect in terms of how long it will take to address the issue. Since this is an engine issue, this issue could be something that causes the car to stall or fail at any time, including while I am in traffic; it could also be electrical, since the battery suddenly died without warning. This would place myself and others on the road in danger. I purchased the battery just over one year ago, so I do not know if there is an issue there.

NHTSA complaint #11623354 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING

The contact owns a 2014 Mazda Mazda3. The contact stated that while driving up an incline at an undisclosed speed, the vehicle temporarily lost motive power, and the contact became aware that the vehicle had failed to shift out of first gear. The contact stated that the vehicle returned to normal functionality; however, the failure recurred several times while driving. Additionally, the contact stated that the instrument panel was functioning erratically, and the instrument panel lights frequently remained illuminated after turning off the vehicle. The check engine warning light was illuminated. The vehicle was taken to the dealer, where the failure could not be duplicated. The vehicle was then taken to an independent mechanic, where it was diagnosed that the head gasket seal had failed, which resulted in an oil leak. The vehicle was repaired, but the failure reoccurred. The vehicle was taken back to an independent mechanic, where it was diagnosed with electrical system failure. The vehicle was not repaired. The contact related the failure to NHTSA Campaign Number: 14V173000(Electrical System); however, the VIN was not included. The manufacturer was not notified of the failure. The failure mileage was 62,000.

NHTSA complaint #11622452 — an unverified report by a vehicle owner.

ENGINE

I was parked in a downtown garage, and the vehicle would not start after many attempts, after about 45 minutes of trying (waiting 5 minutes between tries). The engine would turn normally and sounded like it was trying to start, but didn't fully engage. It finally did after 45 mins, and I drove it to the local Mazda dealer in Honolulu. I noticed the check-engine light was on at that time (but not before the incident). They ran a diagnosis, and couldn't replicate the issue, and said it may be a battery problem with low voltage, due to the engine's error codes. But I questioned that since the engine was able to turn normally and adequately at all starting attempts. And the battery was only 2 years old. So I replaced the battery at their recommendation. About 2 hours after picking up the car from the dealer, the same issue happened again. I recorded the issue on my phone this time, and gave it to the dealer. And this time I didn't want to chance it, so had the car towed back to the same dealer. They couldn't replicate the issue immediately, but after several attempts (over a day), they finally experienced it. They said the issue is the fuel pump. I am the original owner, and had purchased the car new from a Mazda dealership, and it has less than 26K miles on it. I researched previous recalls with this same issue on Mazdas, even the same year and model, and it appears to related: [XXX] [XXX] No one was physically harmed due to this issue, but it was certainly a safety risk. If the fuel pump fails while driving, the driver could lose control of the vehicle while in motion. I have attached the invoices for the repairs. I have contacted Mazda Customer Experience and they assigned a case number # [XXX]. However, I was informed that the repairs are unlikely to be covered as there is no open recall on the VIN regarding this issue. Thank you. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11616920 — an unverified report by a vehicle owner.

ENGINE

Low oil light - car is burning oil and only has 11,400 miles. Approx 3/4 to 1 quart missing...

NHTSA complaint #11615747 — an unverified report by a vehicle owner.

ENGINE

Driving on a remote highway in northern WI and low oil light illuminated, 1000 miles before oil change was due with less than 10k miles on the vehicle. Made it to a gas station and oil was a quart low. Vehicle burns over a quart every oil change interval, since this has been occurring since day 1 it is likely going to cause premature engine failure which would be a safety issue.

NHTSA complaint #11595336 — an unverified report by a vehicle owner.

ENGINE

I had an oil change back in April of 2024. I have been driving the last couple of days and after about 15 minutes my low oil light comes. this car has 58.800 miles on it. I stopped at a oil express to see if I was low on oil but they said I was at full. I also checked to see if they saw anything leaking but they also said they didn't see anything. if the gasket is bad 58,000 that is telling me it's a faulty product. I'm afraid that my engine could lock up on the highway and cause a bad accident.

NHTSA complaint #11592585 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING

The contact owns a 2018 Mazda Mazda3. The contact stated that while driving at an undisclosed speed, there was an abnormal sound coming from the engine. The contact stated while starting the vehicle, the abnormal sound would increase. The contact took the vehicle to an independent mechanic who listened to the engine and ended up removing pistons from the engine. The mechanic discovered there was an abnormal sound in cylinder #3 which caused the mechanic to remove the spark plugs. The contact linked the failure to NHTSA Campaign Number: 17V745000 (Engine and Engine Cooling). The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 118,000.

NHTSA complaint #11587678 — an unverified report by a vehicle owner.

ENGINE

While accelerating onto a highway, my engine overheating light flashed then stayed on and my acceleration suddenly throttled back and my car started slowing down. I was able to pull over on the shoulder, but there was a close call with a semi bearing down. I had my car towed to a repair shop, where they told me the water jacket had cracked and the overheating caused a blown head gasket. This was repaired and tested. A week later, I got the car up to highway speeds and the engine overheating light flashed again. When I stopped and looked at the engine, there was foamy tan coolant all over the place. Towed it back again and was told the weld had failed. But in trying to find a used cylinder to replace mine, the shop told me that all of their sources said they had no used ones available because the same crack happened on those as well.

NHTSA complaint #11583891 — an unverified report by a vehicle owner.

ENGINE

I have a 2017 Mazda 3 with exactly 59,454 miles. I was driving my car into work and a warning came on saying coolant temperatures high pull over immediately. I feel my safety was at risk since I was on a highway and my car lost power and would not allow me to accelerate. Loaded the car on a flatbed to bring into a Mazda dealership. I had oil leaking into my coolant. They diagnosed it as a cracked cylinder head or engine block. Only solution I was given was to replace the engine with a factory new engine. I spoke to Mazda customer service and they admitted it is a known issue.

NHTSA complaint #11582576 — an unverified report by a vehicle owner.

ENGINE

The coolant control valve stays open.

NHTSA complaint #11577126 — an unverified report by a vehicle owner.

ENGINE

Defective Driver's seat construction made by Mazda Mfg Corp. I was the first person to report this cheaply made driver's seat failure to Mazda Corp in Irvine, CA in early 2015 or 2016. Recall was finally issued a year afterwards because Mazda dragged their feet, and only after I threatened to sue them if I was ever in an accident, and the seat was to totally fall apart, and maim me for life did they finally take action. The Recall fix (cheap bandaid clamp that again failed because seat frame welds had failed as well) was never done right, and as a result the seat totally fell apart, and Ed Howard Lincoln Mazda of Sarasota, FL didn't want to do anything further at that point (cost out of pocket wise). I was told by a different Mazda Dealership in Ft Myers, FL that that defective seat should have been totally replaced if they would've handled it correctly. So Ed Howard Lincoln Mazda really screwed me on that one! As related to the 2.5L Mazda engine, I also had/have a engine failure part there as well. It's called the ENGINE COOLANT (WATER) OUTLET FLANGE, and the bottom left hand bolt (1 of 4 bolts total) that's suppose to hold this cheap plastic part in place was stripped (over-torqued) at the production assembly line time that the engine was made (put together). Now the cheap plastic replacement part is leaking again from the same lower left hand corner, and this is a well Known Ford & Mazda 2.5L engine failure design as stated in many a Mazda online forum! This also should have been recalled, as now my 2011 Mazda 3 is down again. Engine overheated again on Oct 13, 2023. Prior repair to replace this defective Flange was done in Feb or Mar of 2022. Cheap Plastic parts put on a Metal engine just don't work well at all. Common Physics would tell you that! I have documents in my storage unit if you need them.

NHTSA complaint #11567016 — an unverified report by a vehicle owner.

ENGINE

TCM has failed to communicate in engine. Car doesn’t not shift properly or has hard shifts if it is able to get back into gear. Car may experience AT engagement making it hard to steer and control vehicle. Can happen in the middle of driving. Independent service Auto mechanic shop Vehicle has no warning lights indicating failure until hard shift when driving 50miles per hour and engine would no longer speed up AT light then came on. Once parked for two days check engine light came on and vehicle no longer would shift into gear.

NHTSA complaint #11564796 — an unverified report by a vehicle owner.