**NHTSA VEHICLE SAFETY COMPLAINT – ENGINE FAILURE AND UNAVAILABLE REPLACEMENT PART** I am filing this complaint regarding serious engine problems with my 2016 Mazda CX-9 equipped with the 2.5L SKYACTIV-G Turbo engine. My vehicle experienced significant engine problems, including overheating, diagnostic trouble codes P0014 (exhaust camshaft timing/VVT system performance) and P0303 (cylinder 3 misfire). Following diagnosis, the cylinder head was found to be cracked, requiring machining and replacement of the timing kit. Despite these extensive repairs and expenses, the vehicle continues to have unresolved engine problems, including rough idling. The vehicle has not been fully repaired because I cannot obtain the exhaust-side Variable Valve Timing (VVT) actuator required to complete the repair. I have been unable to locate this component, and Mazda USA has indicated that the part is not available through its U.S. or Canadian parts network. This leaves me with a vehicle that cannot be properly repaired due to the apparent unavailability of a critical engine component. I find it unacceptable that an essential engine component for a Mazda vehicle cannot be sourced through the manufacturer or its authorized parts network. The situation has resulted in significant financial hardship, prolonged vehicle downtime, and the inability to restore my vehicle to proper operating condition. I am concerned that the underlying engine and VVT-related problems may represent a broader safety and reliability issue affecting other owners of 2016 Mazda CX-9 vehicles equipped with the 2.5L turbocharged engine. I respectfully request that NHTSA investigate the reported engine problems, including overheating, cylinder-head cracking, VVT actuator failures, and the availability of replacement components. I also ask that NHTSA determine whether these conditions represent a safety defect that warrants further investigation or corrective action by Mazda.
- NHTSA ID
- 11774862
- Incident
- Mar 2, 2026
We discovered the problem by accident -- pulled out of our garage and there was a coolant puddle on the garage floor. No dashboard warnings, no overheat messages, no visible symptoms before that. That's what makes this failure mode dangerous: it loses coolant silently, and you find out from a puddle or from an overheat, not from the car telling you. A Mazda dealership confirmed the failure during a multi-point inspection by one of their master technicians (September 2026): coolant leaking from the back of the cylinder head, no signs of coolant and oil mixing, and a scan showing no history of overheating. Their recommendation is cylinder head replacement. The vehicle is available for inspection on request. This exact failure mode is a known design defect on 2016-2020 CX-9s with the 2.5T engine. Mazda itself acknowledged it -- special service program CSP11 ("Coolant Leaks at Cylinder Head Warranty Extension," NHTSA doc MC-11011136-0001, issued October 2024). That program extended the powertrain warranty to 10 years / 120,000 miles for precisely this failure, covering vehicles produced before June 2020 -- which includes this one. Here's the part that gets me: my vehicle is in the CSP11 VIN range, and the defect was diagnosed inside the program's 10-year date window. But the odometer is past 120,000 miles, so coverage was denied. The owner notification for CSP11 didn't go out until November 2024 -- to original owners. I bought this vehicle used, and never received that notice, so the extension was effectively invisible to the person actually driving the car as it crossed the mileage threshold. A manufacturer-documented design defect shouldn't lose all coverage on a technicality for used owners. Cause: UNKNOWN. The crack is at the cylinder head stud bolt hole area, matching Mazda's own documentation (TSB 01-002/23). No maintenance schedule prevents a casting crack.
- NHTSA ID
- 11769435
- Incident
- Sep 10, 2026
Cracked head cyclinder leaking. Unsafe to drive, coolant can leak into engine if not already. They are aware of it and extended a warranty for the issue in 2024. However people like me, my coolant didn't leak until this year 2026. There have been lawsuits on this issue, but they are still failing to address this issue. They created another part to replace the defected part which costs around $6000-$7000. Yes, took it to a Mazda dealer and confirmed the issue and they can fix but cost would be out of pocket. No warning at all. The only way this was discovered was the smell of the coolant leaking.
- NHTSA ID
- 11768085
- Incident
- Jul 15, 2026
My car have a manufacturer engine defect that the company or corporation is not willing to fix. Only because I exceeded the warranty I call them (MAZDA) an told them that it wasn't under my control the these issues happened after the warranty expire. But they still refuse to help me.
- NHTSA ID
- 11765988
- Incident
- Sep 20, 2026
Engine revs or surges while in park, possibly faulty throttle box
- NHTSA ID
- 11757879
- Incident
- Aug 18, 2026
The cylinder head (which involves the engine cooling system) has a known manufacturer defect that affects all year/models of the Mazda CX-9 with turbo. The manufacturing defect poses a risk to motor vehicle safety in a group of vehicles or equipment of the same design and/or manufacturer. Specifically, the overheating and failure of the engine can occur at any time, without warning. This puts my family at risk of being stranded on a roadway, particularly because my car is often driven in rural areas. The manufacturing defect is significant and is acknowledged by Mazda: Mazda has offered owners a voluntary, limited, warranty extension (CSP11) of 10 years or 120,000 miles. The voluntary warranty extension is not sufficient because it is limited in duration while the safety risk can happen at any time after the warranty extension expires. The warranty extension essentially only applies to about half of the expected lifetime of the car. NHTSA should determine that a recall and repair should be issued by Mazda that does not expire. The engine is defective, poses a safety hazard, and Mazda has fixed the engine for subsequent models (starting in 2021), so a repair is available.
- NHTSA ID
- 11734209
- Incident
- Apr 27, 2026
I own a 2016 Mazda CX9 Touring FWD (180k miles). Today my car was diagnosed with cracked cylinder head, resulting in coolant and oil leak from the head gasket. While there is a class action settlement about it where Mazda accepted the manufacturing defect, they do not cover the engine repair/cylinder head replacement because my car's mile is over 120k. If it is a manufacturing defect, why year/mile make a difference on the responsibility of the manufacturer? Mazda obviously sold defect vehicles to their customers, and driving these vehicles under this condition is very dangerous! Now, they are expecting me to pay more than $10,000 for a vehicle priced around $6,000!
- NHTSA ID
- 11706610
- Incident
- Dec 22, 2025
In June of 2022 I started having a strong antifreeze/engine coolant smell inside the cab of my vehicle and also outside the vehicle. I had the car checked for a radiator leak, but there wasn’t one. I took my car into my local Mazda where they found that the engine coolant was leaking into the heads of the engine. Mazda kept my car for 5 months and repaired the problem, it cost me $4000 and they had added a 12 month 12,000 mile warranty for the parts. My car is a 2016 Mazda cx-9 at the time of the repair it had 70,430 miles on it. Now a few years later I am having the same issue with the coolant smell inside the cab and outside my vehicle, it goes into the shop for diagnosis on Monday November 10,2025. The car now has 118,000 miles on it. I had purchased an extended warranty for the car at the time of purchase but it had timed out a month before I took my car in for the first repair….please Mazda stand behind your vehicles I am a senior woman with very little income and I will not be able to pay out of pocket for this repair and I CANNOT afford a new car… I would like to get reimbursed for my out of pocket on the first repair and get my car repaired this time as well under a warranty.
- NHTSA ID
- 11697196
- Incident
- Jun 30, 2025