2018 Mazda MAZDA3

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.

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.

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)

The contact owns a 2018 Mazda Mazda3. The contact stated that while his girlfriend was driving at 65 MPH, several unknown warning lights illuminated, and the vehicle stalled. The contact stated that his girlfriend was able to safely drive the vehicle to her destination. The vehicle was then towed to the dealer. The vehicle was diagnosed with rod knocks. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 105,000.

The contact owns a 2018 Mazda Mazda3. The contact stated while driving 60 MPH, the vehicle inadvertently lost motive power. After restarting the vehicle, the vehicle returned to normal functionality. No warning lights were illuminated. The vehicle was towed to an independent mechanic, who was unable to determine the cause of the failure. The vehicle was then towed to the dealer, who determined that there was no oil in the engine. The manufacturer was not notified of the failure. The failure mileage was 105,000.

I have a 2018 Mazda 3. On two occasions in the span of one month, my car has acted like it was going to stall out when I was stopping at a red light. It doesn’t stall out, but the car will idle like it’s about to stall. When starting the vehicle it is kind of sluggish at times. Battery has been tested and it is fine. I’ve had the car for five years and it has 60,000 miles on it. No issues until recently.

I was driving my car and it suddenly jerks a few times and the engine light turns on. i slowed down and then began to accelerate, and it was losing power and wouldn’t t go above 40mph - even while flooring the gas pedal. Now it won’t start at all. the lights turn on and everything else is fine, but car won’t start and after checking CEL, i’m getting the code p0192 indicating it’s Fuel Rail Pressure Sensor Low Input.

The contact owns a 2018 Mazda Mazda3. The contact stated while driving 25 MPH, the vehicle stalled inadvertently. The contact was unaware if there were any warning lights illuminated. The contact was able to veer to the side of the road; however, the vehicle failed to restart. The contact's husband added fuel to the vehicle; however, the failure persisted. The contact stated that the vehicle restarted 15 minutes later. The vehicle was taken to an unknown dealer who informed the contact that the failure could not be duplicated because there was no warning light illuminated. The vehicle was not diagnosed or repaired, and the failure persisted. The contact stated that the failure reoccurred upon shifting from reverse(R) to drive (D). The power train warning light and several unknown waring lights were illuminated. The contact was able to restart the vehicle and continued driving. The manufacturer was not notified of the failure. The failure mileage was approximately 32,000.

On March 29, 2021, I had my 2018 Mazda 3 serviced, oil and filter chance, and inspection, at my local Auto repair shop. They indicated that the belt tensioner and belt needed replacement, due to oil leaking, from the tensioner, on to the belt. I got concerned because the vehicle only had 11,523, and the warranty ran out a few weeks earlier. I emailed Mazda several times, and asked, due to the low mileage, and close to warranty expiration, for their dealer to inspect the vehicle, and if needed, replace the tensioner and belt, both free of charge to me. They declined to grant me that courtesy.

THE BATTERY IN MY 2018 MAZDA 3 (TOURING) HAS DIED 3 TIMES IN ABOUT YEAR'S TIME. AFTER THE FIRST TIME, THE DEALER SAID IT WAS JUST A FLUKE--THAT IT COULD HAVE BEEN CAUSED BY ANYTHING. THEY PUT A BRAND NEW BATTERY IN. AFTER THE SECOND BATTERY DIED, THE DEALER SAID THAT IT WAS BECAUSE WE WEREN'T MAKING LONG DRIVES IN THE CAR. THEY REPLACED THE BATTERY WITH A BRAND NEW ONE--AND THEY ASSURED ME IT WASN'T ANYTHING ELSE INCLUDING THE ALTERNATOR (I ASKED ABOUT THE ALTERNATOR SPECIFICALLY). NOW, THAT BATTERY HAS DIED. I WILL CALL THE DEALER TOMORROW TO HAVE A FOURTH BATTERY INSTALLED.... THE VEHICLE WAS STATIONARY--EITHER IN OUR GARAGE OR DRIVEWAY--WHEN WE REALIZED THE BATTERY WAS DEAD. IF YOU WOULD LIKE TO SEE THE RECORDS OF MY VARIOUS VISITS TO THE MAZDA DEALERSHIP, PLEASE CONTACT ME. *TR