Owner-reported complaints naming the engine system, filed with NHTSA
Data refreshed
Reports naming the engine itself — including stalling, misfires, oil consumption, cooling and internal engine components. Every record below is an owner-reported complaint about the 2021 Mazda CX-9 submitted to NHTSA — not a confirmed defect, not a recall and not a manufacturer bulletin. 20 reports on file name it.
Complaints are reports submitted by owners and drivers to NHTSA. They are not verified and do not establish that a defect exists.
Shown in the owner’s own words, exactly as filed
The vehicle was parked stationary in the driveway with the engine running for 3-5 minutes with the A/C on. The vehicle then accelerated forward into my garage causing damage. Once I entered the vehicle, both the dash and shifter displayed park. Current TCU system internal failures have been reported from the pulling of data from Mazda.
1) What component or system failed or malfunctioned: On 6/12/2026 While drive on the highway with our daughter in the car and we experienced a high speed stall. The engine failed and we lost power. We barely got the car of the highway and coasted into a parking lot. 2) Life threating for Father, Mother and daughter and other drivers on the highway. 3) The Mazda dealer stated they were unable to reproduced problem. The diagnostic report showed few random misfired on two cylinders 2 & 3. Autozone detected codes P0300 with Secondary DTCs U0442-00 4) There car was only inspected by the dealer. The vehicle has not been inspected by Mazda the manufacturer. We requested Mazda to escalate this to the District Service Manger and to open hotline call with Mazda corporate but both of these were denied. All our service has been performed at Mazda dealer, including oil changes. We have always received a video of them working on our car with a detailed summary of what done. We did not receive the video or diagnostic report for this issue. 5) There were no warning lamps, no messages or other symptoms of the problem prior to the failure.
This complaint refers to Mazda and it's dealer refusal to properly execute the warranty work under the SSPD5 Valve Stem Seal Class Action Campaign and does not follow the Court's approval of the final Settlement Agreement. I assert that Mazda and it's dealer are not following the SSPD5 repair procedures. 1. I have documentation and complaints going back to Dec-2023 with this particular dealer that I have experienced low level oil consumption within the 7,500 mile oil change interval. The dealer did not detect oil leaks in any of the engine systems. 2. I presented the vehicle to the dealer with the Engine Oil Level Warning Light illuminated. The Diagnostic Trouble Code (DTC) P250FF:00 should be stored in the vehicle memory. 3. The vehicle had 50,501 miles and was within the original 60 month limited powertrain warranty. 4. The dealer refused to conduct the valve stem seal repairs until an oil consumption test was run. The dealer claims that because I had another service center (note that I use full synthettic oil that meets Mazda oil specifications) conduct the most recent oil change at 43,738 miles (note within the 7,500 oil change interval and the 1 year time window) that the dealer would require an oil consumption test. I assert that this is not required per the class settlement agreement and the SSPD5 repair procedures that Mazda sends to all of its dealers. 5. I researched the available documentation that it's available through the NHTSA.gov. The language in these documents is very clear. 6. SSPD5 Valve Stem Class Action Campaign, Repair Procedure 6-12-2024: a. "The DTC250 is not required to be present for valve stem replacement." b. "Customer complaint of oil consumption...OR Low Oil Light OR DTC250 follow the flow chart." c. Flow chart says "Replace the exhaust valve stem seals by following TSB 01-003/24" if no previous warranty work done. 7. SSPD5 updates on 8-6-25 and 4-28-26: a. Refer to page 4, DTC250 is NOT required to be presented (it is noted in RED).
Check engine light comes on and error P0303 comes on. Had an independent mechanic do the following and after each one, error P0303 still came on 1. Swap the ignition coils from 2 to 3 2. Swap spark plugs from 2 to 3 3. Swapped injectors 4. Compression test 5. Leak down test 6. Changed the spark plug, coil and injectors 7. Looked for vacuum leaks. Mechanic believes that it is related to the cracked cylinder head in the recall, MC-10232269-0001.pdf. My vehicle is just outside of the recall range and has 87k miles on it. Other research online shows other people with the same vehicle and similar milealge are also having this problem.
Car loses oil and coolant rapidly
The contact owns a 2021 Mazda CX-9. The contact stated that while accelerating quickly and entering the highway, there was no motive power to the vehicle. While crossing the highway in the right lane, driving at 65 MPH, the vehicle in front moved over; there was a parked vehicle. The contact was able to stop the vehicle before causing a crash. The driver was starting to accelerate, but there was no motive power when the accelerator pedal was depressed. The smart brake system malfunction message was displayed. There were no warning lights illuminated. The contact called the local dealer, who scheduled an appointment. The vehicle was not diagnosed or repaired. The manufacturer was contacted and informed the contact to have the vehicle diagnosed. The failure mileage was approximately 53,186.
Consumes over 2 quarts of oil between recommended oil changes. The dealer made excuses about needing to use a different oil but it has not improved the problem. The warning light for low oil went off after less than 3000 miles. It was 2 quarts down.
I just purchased this vehicle 2 months ago. Yesterday my oil light came on, I pulled over and checked the oil it was completely low. I had to put a quart of oil in it. After that I did some research and learned this seems to be an issue with some 2021 models the cx9 included. There needs to be a recall on this and Mazda needs to fix this issue. These cars cost way to much to have to put a quart of oil every month.
Oil light came on, vehicle has ~15,000 miles.
the vehicles experience excessive oil consumption because the defective valve stem seals allow engine oil to leak into the combustion chambers. This concern usually occurs when the mileage reaches approximately 2,000 – 3,000 miles (5,000 - 7,500km) and may also occur again after replacing or topping off the engine oil.
2021 Mazda CX-9 Low Oil Light came on at around 18,900 miles (2/10/2023 and 2/11/2023). Took to Mazda, and they said there was defective valve stem seals that can allow oil to leak into the engine’s combustion chamber. Vehicle is currently with Mazda service department to be fixed.
The contact owns a 2021 Mazda CX-9. The contact stated that while driving at 60 MPH or exceeding 60 MPH, the vehicle would lose motive power and stall without warning. The contact stated that he would coast to the side of the road and the vehicle would restart after 2-3 attempts and regain normal functionality. The vehicle had not been diagnosed or repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 49,000.
A LOT OF ENGINE OIL CONSUPTION, 1 QUART PER 2500 MILES.
My 2021 Mazda CX-9 uses excessive engine oil as reported in the Mazda "M-Tip" bulletin MT-005/20 and this manufacturer's defect is reportedly caused by defective valve stem seals as claimed in the class action lawsuit U.S. District Court for the Central District of California, Southern Division: [XXX] v. Mazda Motor of America, Inc. The valve stem seal problems allegedly cause excessive oil consumption between regular oil change intervals, which increases the risk of engine damage and failure. I believe Mazda must address this issue as soon as possible and repair my affected vehicle before I suffer catastrophic engine failure or long-term engine damage. INFORMATION Redacted PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6).
1000 miles before first ever oil change was needed (according to window sticker provided by Mazda) the low engine oil light came on. The oil was low and needed to be toped off and brought directly to dealer for oil change. The same thing happened again 1300 miles before second oil change was required. It became obvious that the brand new vehicle was burning oil for some reason. The dealership tried to tell us that it was because the car was a turbo. We weren’t buying it and told them we wanted it looked at. After brining it into the dealer they mentioned that Mazda had a bulletin for a valve seal fix that might help it stop burning oil. So they admitted that yes it was burning oil. After googling the bulletin I realized that our vehicle is having the same problems that many others with 2021 Mazdas (certain production period) are having. There is currently no recall however there is proof that these problems are damaging our vehicle, putting my wife and children at risk every time they get in the car and Mazda is doing nothing about it. There is also proof that these gases from the burnt oil are damaging other engine systems further increasing the likelihood of an engine failure. Down the road. Chances are this damage is already done, despite this valve seal repair.
Massive oil consumption. Uses 1 quart or more of engine oil at around 3,000 miles after oil change. Low oil light comes on...
The low engine oil light is coming on every 3500 miles. When checking oil level it indeed is low and requires a quart of oil. There is an active TSB out as this is a known issue but no recall issued yet.
New Mazda vehicle engine is consuming approximately 1 quart of oil, approximately every 3,500 miles. No recall for this yet, however Mazda technical service bulletin TSB # 01-012/21 admits this is a common and known issue for this vehicle which may eventually lead to the vehicles engine and parts no longer functioning.
Every 4,000 miles my engine oil warming light comes. When the dealership checked my oil level, it was about a quart low.
I purchased this vehicle June 5 2021. The vehicle has approximately 9150 miles at this time. I changed the oil the first time at 3222 miles just because it was new and I wanted to have a starting point on oil changes. The car has an app you load on your cell phone for messages. The first time I received a massage that the engine was low of oil was around 6700 miles. I checked it and it was low with at the add oil mark with 3500 miles driven. I received a second message from the app stating the oil was low. Again, I checked the oil and it was to the add oil level with 9014 miles or only been driven 2300 miles. I have contacted Mazda and will take it to the dealership in a few days, but I am having to add and check the oil ever day or so. There seems to be an oil consumption issue with this engine.
Higher-selling and older vehicles accumulate more reports. Counts are not failure rates and are not directly comparable between vehicles that sold in very different numbers.
Data on this page last refreshed .