2018 Mazda Mazda6 Complaints

Tether, Lower Anchor (on car seat or vehicle),Other/I am not sure — Filed 05/16/2026

Have had 3 seats replaced under warranty by Graco and was told to make a report with you. The rigid latch anchors on two have been faulty after 2 months. The second one got stuck in the installed base and pulling the release button did nothing. The rigid latch on the first got stuck in the open position. The second they would move independently of each other and not lock in. The third is starting to have the same issue with getting stuck in the base. These have all happened within two months of normal use.

WHEELS,FUEL/PROPULSION SYSTEM — Filed 08/28/2026

Fuel pump is leaking, just as all the other 2018-2020 fuel pumps but mine doesn’t qualify for the recall.

ENGINE — Filed 08/07/2026

The car only has 70k miles on it. The engine started smoking under the hood. Immediately stopped to look. There was oil leaking but I could not see from where. I took it across the street to the Toyota dealership and had them look at it. They explained to me that there was a crack in the cylinder head and oil was leaking everywhere. Potentially causing a fire or even an explosion. The old was leaking all over the exhaust manifold and engine. I had my 2 toddlers in the car not long before this happened. This is extremely unacceptable. Currently Mazda is saying it will be 7200 to replace the engine and that cost is on me. I think that is absolutely absurd being there are only 70k miles on the car and I bought it brand new. I also kept up with all of the required maintenance.

STEERING,SUSPENSION,VEHICLE SPEED CONTROL — Filed 07/29/2026

Got error message that said "Forward Smart City Brake Support Malfunction" slso fot "smart brake malfunction" while driving. The ac stopped, the car speedometer kept going from 50 to zero. The car died and couldn't open doors, windows. Lost steering while driving. We were able to get off road and restart and fine for 2 weeks. While at still light tonight, the car turned off. Windows were up, couldn't open door, emergency blinkers would not come on. This is very dangerous.

ENGINE — Filed 04/25/2026

Crack in Cylinder Head of engine. Mazda has been sued about this and have issued recalls on turbo engines, but not on non turbo ones though its the same systemic design issue with these engines. Wants me to pay 5-7k out of pocket.

ENGINE — Filed 06/01/2025

My cylinder head is leaking coolant. There is a well known and well documented issue with these cylinder heads cracking due to poor casting. This has become such a big issue that Mazda has even recalled the cylinder heads, BUT, only if the engine is equipped with Turbo. However, this issue is becoming enormous even for non turbo owners and is a huge safety issue as it can lead to overheating, stalling, and further damage to other components. I feel very strongly that it is time for Mazda to take some responsibility and extend the cylinder head recall to the non turbo engines.

ENGINE — Filed 04/04/2026

Car had a coolant leak due to cracked cylinder head that was defective from the factory it was fixed but now the car has engine problems again. Don’t want to keep having these issues in the future

POWER TRAIN — Filed 03/02/2026

System Failure: The Power Train (6-speed Automatic Transmission) suffered a major malfunction, documented by diagnostic codes P0731 (Gear 1 Incorrect Ratio) and P0780 (Shift Error). The vehicle is available for inspection. Safety Risk: The failure caused a sudden loss of propulsion while attempting to accelerate. This created an immediate risk of a rear-end collision and left the vehicle unresponsive in the path of oncoming traffic. The transmission's unpredictable shifting makes the vehicle unsafe to operate. Confirmation: The failure and the P0731 code were officially confirmed by Castle Mazda on March 2, 2026. The manufacturer (Mazda) has been notified but has denied a remedy, despite TSB MC-10160555-0001 addressing this specific internal defect. Warning Symptoms: There was no Check Engine Light or dashboard warning prior to or during the failure. The only warning was an extreme, abnormal mechanical grinding/clunking noise from the transmission. The lack of a malfunction indicator light (MIL) meant I had no electronic warning of a looming mechanical failure while in motion.

ENGINE — Filed 02/13/2026

Per Mazda inspection, the back side of cylinder head #3 has an oil leak which is leaking onto the exhaust manifold. This creates a direct fire hazard as Mazda said they highly recommend not driving it for that reason. The Mazda dealership inspected and confirmed the issue, it in February 2026, with only 74,000 miles on the vehicle.

POWER TRAIN,ENGINE — Filed 12/23/2025

I recently discovered a significant oil leak near the exhaust manifold of my 2018 Mazda 6 (2.5L NA), which has resulted in visible smoke and a burning oil odor. Upon taking the vehicle to the nearest Mazda dealership for a diagnosis, the service department informed me that the vehicle has suffered a cracked cylinder head. An active oil drip is visible behind the engine near the exhaust manifold immediately upon starting the car; consequently, the engine is leaking oil directly onto the exhaust components. This condition not only renders the vehicle inoperable but also presents a significant safety and fire hazard. At the time of this writing, my vehicle has only 46,996 miles and has been meticulously maintained. This mileage is well under the 60,000-mile powertrain threshold and represents a premature failure of a major internal engine component. There are numerous reports on Mazda owner forums describing this identical issue occurring in Mazda 6, CX-5, and CX-9 models. Some owners have even reported instances of minor fires or active burning under the hood due to oil contacting hot engine components. Mazda released Technical Service Bulletin TSB #MC-10241612-0001 (SA-037-23), which includes a redesigned cylinder head for 2018–2020 Mazda 6, 2019 CX-5, and 2016–2020 CX-9 models, demonstrating Mazda’s awareness of this design flaw. While the TSB currently only specifies the 2.5L Turbo engines and not the naturally aspirated variants, there is substantial evidence that this is a widespread defect across these model years, unrelated to owner misuse or vehicle mileage. Mazda should take full responsibility by issuing a formal recall or providing an extended warranty to cover naturally aspirated engines, thereby addressing this problem and preventing further safety risks.

ENGINE — Filed 10/11/2025

Cracked cylinder head causing oil leak and possible coolant leak. This is a known issue with this year and model. Mazda is trying to suggest the issue is only for the turbo engine, but the non-turbo engine is also defective, per countless reports online. I have a video from the service technician from the mazda dealership, but it is too big to upload.

POWER TRAIN — Filed 07/25/2025

Was driving then car suddenly shut down and all panel lights turned on. The car would not start after an hour it started but was Perkins when driving. Mechanics were unable to diagnose the issue.

SERVICE BRAKES — Filed 05/06/2024

Premature caliper failure on front and rear. Ruined rotors at 40k miles, confirmed caliper failure by two service shops. Grinding/squeaking sounds intermittently been happening for since 30,000 miles

FUEL SYSTEM, GASOLINE — Filed 03/26/2025

The contact owns a 2018 Mazda Mazda6. The contact stated upon taken the vehicle to the dealer for an oil change, the dealer notified the contact of a fuel leak. The dealer diagnosed the vehicle and informed the contact that the top of the fuel tank and bolts connected to the fuel pump were significantly rusted, causing the fuel leak. The dealer determined that the fuel tank and the fuel pump needed to be replaced. The vehicle was repaired. The manufacturer was notified of the failure and informed the contact that no assistance would be provided because the contact had already authorized the dealer to repair the vehicle. The failure mileage was approximately 75,000.

ENGINE — Filed 04/18/2025

Bought used with 47k miles. Two weeks later, took it to my mechanic for an inspection, they found a massive oil leak on the back of the motor. Took it back to the dealership and they diagnosed it as a cracked cylinder head, for which there is a known TSB and warranty extension. Unfortunately, the warranty extension only covers a coolant leak from the cracked cylinder head, not an oil leak. Thankfully, the dealership took care of me but had they not, I was looking at a $7k+ repair on a car I had owned for 2 weeks. In the TSB, Mazda acknowledges that there were both design and manufacturing flaws for the affected model years. In acknowledging the issue, they should have issued a recall for affected vehicles, not a simple warranty extension

SERVICE BRAKES — Filed 03/05/2025

I am having my brake pads changed at a local mechanic and when changing the pads, the mechanic was unable to change them because the rotors and calipers were rusted and the brake pistons stuck. The previous recall only considered Mazda 6 up to 2013 but my 2018 has had the same problem.

UNKNOWN OR OTHER — Filed 01/14/2025

Software error/loss of engine power. No warning of this before it happens. The car completely loses power, and stalls or stops in the middle of me driving. This has happened on the freeway and risked my life as well as my husbands, and children. This same issue has been a previous recall and fixed in 2019 for my car, and now it is happening again.

UNKNOWN OR OTHER,ENGINE — Filed 12/10/2023

Coolant leaks at the cylinder head around the exhaust manifold causing my car to over heat. Also when my thermostat is set to the exact temperature for both sides my driver side blows cold and the passenger side blows hot

ENGINE — Filed 12/22/2024

Driving in traffic and the engine temperature warning appeared on dash. Dealer has confirmed there is a large coolant leak from the cylinder head. Mazda released a technical service bulletin regarding the issue affecting Mazda6, cx-5 and cx-9, but I will have to pay for a head gasket replacement.

ENGINE — Filed 11/18/2024

Cracked cylinder head near the exhaust manifold. Created a large oil leak. Oil on the exhaust is a fire hazard. After one quart of oil loss a low oil level light comes on. This is a reported problem. One version of the engine I have has a Mazda TSB and an extended warranty. TSB 01-0022/23 A local repair shop has diagnosed the problem.

UNKNOWN OR OTHER,ENGINE,FUEL/PROPULSION SYSTEM — Filed 09/28/2024

My car has stalled out on me 6 times in traffic and wouldn’t restart for hours. I took it to the Mazda dealership and they told me nothing was wrong but it continues to happen. I need something done as soon as possible

ENGINE — Filed 09/11/2024

Cracked Cylinder Head. At 50,400 miles. This is far too common of a problem for such a new car with so few miles. I have seen many similar reports online. My mechanic was baffled. This is a $5k cost AT LEAST. Mazda has a history of not covering these defects. And it IS a defect, not a simple wear and tear issue. A cracked cylinder head can eventually lead to engine failure, so it is dangerous to drive with it. The problem HAS been confirmed by an independent service center. I got a oil pressure warning sign.

ENGINE — Filed 07/08/2024

The contact owns a 2018 Mazda 6. The contact stated that while merging onto a freeway the vehicle did not accelerate while pressing the accelerator pedal, lost automotive power. After turning the engine off and back on the vehicle operated as normal but later while driving approximately 65 MPH the failure had reoccurred while attempting the pass a semi-truck on the freeway. The check engine warning light had also illuminated and the vehicle was eventually towed to the local dealer who was unable to determine the cause of the failure. The vehicle was not yet repaired. The manufacturer was not yet contacted. The failure mileage was 67,000.

ELECTRICAL SYSTEM,UNKNOWN OR OTHER,ENGINE — Filed 05/25/2020

MY MAZDA6 SPONTANEOUSLY CAUGHT ON FIRE WHILE IT WAS PARKED ON A STREET AND COMPLETELY BURNED DOWN. THE FAULT/PROBLEM CAUSE IS UNKNOWN AT THIS TIME BUT I SUSPECT THERE WAS WIRING/ELECTRICAL FAULT AND MANUFACTURING AND DESIGN DEFECT. BOTH THE SHERIFF'S DEPARTMENT AND FIRE DEPARTMENT WERE INVOLVED IN ASSISTING ME IN THIS INCIDENT. I AM STILL WAITING FOR REPORTS FROM LAW ENFORCEMENT/FIRST RESPONDERS. MAZDA HAS REFUSED TO ADDRESS THIS SITUATION WITHOUT ME PROVIDING THEM WITH AN "INSPECTION REPORT SUPPORTING THE CLAIM A DEFECT WAS PRESENT AND SAID DEFECT CAUSED THE FIRE." AS I WAS ONLY A LESSEE OF THE VEHICLE, I HAVE NO POSSESSION OF THE VEHICLE AND, THEREFORE, I CANNOT ORDER AN INSPECTION ON THE VEHICLE. MAZDA IS ACTING IN BAD-FAITH.

SEAT BELTS — Filed 11/22/2019

TL* THE CONTACT OWNS A 2018 MAZDA 6. WHILE THE CONTACT'S FRIEND WAS DRIVING 55 MPH, HE VEERED OFF THE SIDE OF THE ROAD INTO A DIRT PATCH, AND STRUCK AN OBJECT. THE AIR BAGS DEPLOYED AND THE DRIVER'S SEAT BELT UNBUCKLED UPON IMPACT. THE AIR BAG DEPLOYMENT BURNED THE CONTACT'S RIGHT UNDERARM. MEDICAL ATTENTION WAS NOT RECEIVED. A POLICE REPORT WAS NOT FILED. THE CONTACT'S FRIEND WAS ABLE TO DRIVE THE VEHICLE BACK TO HIS APARTMENT. THE VEHICLE WAS NOT DIAGNOSED OR REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE AND DID NOT ASSIST. THE DEALER WAS NOT CONTACTED. THE FAILURE MILEAGE WAS APPROXIMATELY 18,000. *DT CONSUMER STATED PARTIAL RETRACT DUE TO PRETENSIONER FIRING. CANNOT BUCKLE ' 8 IN TOO SHORT. BOTH HANDS ON STEERING WHEEL. WEIRD SEAT BELT UNLATCHED.*JB