Coolant leak from a cracked cylinder head that mazda is aware of and released a TSB about. Refusing to extend warranty or fix due to being 6 months out of 60 month power train warranty. Still under 60,000 miles.
2017 Mazda CX-9 engine problems
moderate 34 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
34
Recalls
0
Avg fix
$3,100
What stands out
Owners have filed 34 engine complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Among the 14 model years of Mazda CX-9 in our records for engine problems, this one ranks #3 by owner-complaint volume.
The failure pattern owners describe
Buyer takeaway: The 2017 CX-9 2.5L turbo has a known cracked cylinder head defect Mazda refuses to recall; you'll pay $3,500–$10,000 out of pocket after the 60-month warranty expires, even though this is a manufacturer design flaw. Avoid this model if you can't stomach that risk.
The 2017 Mazda CX-9 with 2.5L turbo engines is developing cracked cylinder heads between 50,000 and 93,000 miles, causing coolant leaks that Mazda has documented in multiple Technical Service Bulletins (TSB 01-013/21, TSB 01-002/23, CSP11) but refuses to recall. Owners report cracks typically form near exhaust manifold studs, allegedly due to insufficient metal thickness or excessive stress from turbocharger weight.
Symptoms vary: some see a large coolant puddle under the car with no warning lights; others experience sudden engine overheating on the highway with red warning lights, forcing an emergency pullover. A few report rough idle or hot coolant smell before failure. The dangerous part is that many owners get zero advance notice—the engine can lose all coolant and power within seconds.
Mazda denies warranty claims and Good Faith repairs once vehicles exceed 60 months or 60,000 miles, even though owners religiously serviced at dealerships. Repair costs range from $3,500 to $10,000 depending on whether only the head is replaced or the entire engine. One owner had a "redesigned engine" fail again in 14 months, then faced a second $6,000 bill. Owners cite online complaints dating to 2016 across CX-9, CX-5, and Mazda6 models, plus a class-action lawsuit, yet Mazda has not extended coverage or recalled the vehicles.
Same Mazda CX-9 engine reports on nearby years: 2014 · 2015 · 2016 · 2018 · 2019
Failure modes owners describe
Cracked Cylinder Head with Coolant Leak
Cylinder head develops cracks, typically near the exhaust manifold studs or in areas stressed by turbocharger weight, causing coolant to escape from the engine block. In severe cases, coolant leaks internally into the engine, damaging internal components. Owners report this is a known design flaw affecting 2.5L turbo engines in 2016–2020 model-year CX-9s, CX-5s, and Mazda6s.
When: Between 50,000 and 93,000 miles; often occurs without warning; one owner reported failure after 89,000 miles following a check engine light three months prior
Symptoms owners cite: Coolant reservoir empty or critically low; Visible coolant puddle under vehicle or caught by heat shield; Smell of hot coolant or antifreeze; Engine overheating warning light (red zone); Loss of engine power while driving; Rough idle or rough running at stops; Vehicle stalling on highway in extreme cases; No warning lights in some instances until failure is imminent
Codes mentioned: TSB 01-013/21, TSB 01-002/23, CSP11
Repairs/costs cited: Full cylinder head replacement or full engine replacement depending on severity; owners cite repair costs ranging from $3,500 to $10,000 out of pocket; one owner reported first repair ~$9,000 for full engine, then head replacement for ~$6,000 fourteen months later; repair backlogs reported up to 9 weeks
Recalls/TSBs owners mention: Mazda issued Technical Service Bulletins (TSB 01-013/21, TSB 01-002/23) acknowledging the defect; however, Mazda has declined to issue a recall or extend warranty coverage; owners say Mazda denied Good Faith repairs and warranty claims citing vehicles are out of the 60-month powertrain warranty or beyond mileage limits, despite acknowledging the design flaw; one owner notes TSB coverage was finally extended in Feb 2023 to include their vehicle after years of known issues
Engine Overheating and Loss of Coolant
Rapid coolant loss from the cylinder head crack causes the engine to overheat dangerously while driving. Temperature warning systems activate, and in worst cases, the vehicle loses all drivability within seconds. This poses an immediate safety risk as owners lose control and must pull over abruptly on highways or major intersections.
When: Can occur suddenly with no prior warning; some owners report smell of hot coolant before overheating event; one owner reported a check engine light three months before final failure
Symptoms owners cite: Temperature warning light illuminates in red zone; Engine temperature gauge climbing rapidly; Warning messages to pull over and turn off engine; Sudden loss of engine power; Vehicle becomes undriveable within seconds of overheating warning; Hot coolant smell before or during event
Codes mentioned: Engine temperature sensor fault
Repairs/costs cited: Prevents driving vehicle; immediate towing required; owners cite risk of engine seizure if driven while overheating
Recalls/TSBs owners mention: No proactive safety notification or recall issued; owners report Mazda acknowledged the issue when questioned but refused to issue recall or extend warranty
Internal Coolant Leak into Engine Block
In severe cases, coolant leaks not only externally but also enters the engine block itself, contaminating the oil and damaging internal engine components. This is the worst-case scenario of the cylinder head crack defect.
When: Occurs when crack progresses untreated; one owner reports being fortunate to catch leak before internal damage occurred
Symptoms owners cite: Coolant leaking into the engine; Oil and coolant mixing inside the block; Internal engine component damage; Total engine failure requiring replacement
Repairs/costs cited: Requires full engine replacement; costs exceed cylinder head replacement; one owner's estimate was $10,000 for full engine replacement
Synthesized from 34 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 14 most recent
2017 Mazda CX 9 signature engine failure at 89,000 miles. July 2021 check engine light came on, this was three months prior to failure. Was told it was a known computer issue and was charged over $200 to fix. November 2021 car started running hot while driving down the road. Red thermostat came on while driving. Was able to get the vehicle to the Mazda dealer that has done routine service on the…
This problem has been documented and know by Mazda for awhile. They are aware that their 2.5 Turbo liter engine has the problem of cracking the cylinder head due to some overweight of the same engine component. My Mazda local dealer already inspected the car and told me that the fix is replacing the whole cylinder head, which with them would cost me 3.5k. My warranty company, which I purchased…
Coolant leak. Cracked cylinder head in a stud hole of the exhaust manifold. 70,000 miles Seems to be a problem with many other owners.
On 11/21/23 Mazda dealership informed that coolant leak in my Mazda CX-9 had ruined the engine. Research on the coolant leak has found several other cases in CX-9 models. It has been alleged that the engines in these vehicles may be prone to coolant leaks around the cylinder head and exhaust manifold joint due to excessive forces. When an engine coolant leak occurs, the vehicle may rapidly…
I was driving to work with my daughter and my engine overheated out of nowhere and caused us to almost be rear ended
Leak from cylinder head caused by overheating. Reported a coolant leak prior to diagnosis. Car now shows an over heat code. Safety was put at risk due to immediate need to pull over and no longer able to drive the vehicle. Dealership and initial shop had different diagnosis of the vehicle. Shop advised of a head gasket leak only. Only warning maintenance light came on as car began to…
2017 Mazda CX-9 with crack in engine with coolant leaking out. Informed by mechanic that coolant was leaking out from the engine and was caught by heat shield. I smelled coolant, but never saw any on the ground. Per TSB 01-002/23 there is a crack that can develop in the engine due to stresses from the turbo/exhaust. A crack will develop near studs in the engine. Once crack develops, the coolant…
coolant leaks from cracked cylinder head which cause the car to overheat and have the engine stalled on the highway.
My car gave me a warning that it was overheating... and gave me a warning to pull to the side of the road because of safety and turn off my car engine because the engine is overheating. I was on the highway when this occurred. The engine coolant light was well into the red zone. I had my two kids in the car and my service animal... The car was say overheating and blinking the engine coolant red…
Had engine trouble with your 2017 Mazda CX-9?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the engine problem on the 2017 Mazda CX-9?
It's a documented issue but not catastrophic. 34 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Mileage data is limited for this issue. Owners report failures across a wide range, suggesting cause is more about driving conditions and maintenance than mileage alone.
What does it cost to fix?
Independent shops typically charge around $3,100 for engine repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to engine?
No active recalls currently cover engine issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2017/Mazda/CX-9.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.