This bulletin supersedes the previously issued bulletin(s) listed below. The changes are noted in Red. 01-008/23 06/05/23 Some vehicles may exhibit rattling noises from the engine compartment and oil leakage from the drive belt auto tensioner. This may be caused by insufficient sealing at the drive belt auto tensioner damper when the auto tensioner fully operates under both high ambient temperature and high load conditions. To eliminate this concern, the shape of the drive belt auto tensioner damper has been changed. REPAIR PROCEDURE If the tensioner is found to be "No Good" after completing the Drive Belt Auto Tensioner Inspection, replace it with a modified part according to the instructio
full bulletin at NHTSA ↗2018 Mazda CX-9 powertrain problems
moderate Owners of the 2018 Mazda CX-9 have filed 12 NHTSA complaints about the powertrain at roughly $2,500 to repair (U.S. federal records, as of August 2026). Source: NHTSA Office of Defects Investigation. See powertrain across all vehicles →
Complaints
12
Recalls
0
Avg fix
$2,500
| Model year | powertrain complaints |
|---|---|
| 2014 CX-9 | 7 |
| 2015 CX-9 | 3 |
| 2016 CX-9 | 8 |
| 2018 CX-9 (this page) | 12 |
| 2019 CX-9 | 4 |
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This Service Alert supersedes the previously issued SA listed below: The changes are noted in Red. SA-011/24 02/12/24, 06/06/24, 07/29/24 DESCRIPTION Mazda has developed factory recommended scheduled maintenance services that support all major vehicle systems. Mazda recommends dealers follow the scheduled maintenance tables as cited in the vehicle-specific workshop manual or owner's manual. Services performed outside of Mazda's factory scheduled maintenance are not recommended. These services are unnecessary and create unneeded expenses for your customers. SCHEDULED MAINTENANCE Refer to the applicable Workshop Manual or Owner's Manual for vehicle -specific manufacturer scheduled maintenance.
full bulletin at NHTSA ↗When inspected, the differential or PTO oil is dark or black. This is considered normal and NO repair should be performed. During production, differential ring and pinion gears receive a manganese phosphate coating (commonly referred to as black oxide). This coating forms a porous, oil-retentive surface that improves boundary lubrication and reduces adhesive wear during initial contact cycles. Designed as a sacrificial layer, it is gradually removed under load throughout the break-in process. As a result, after the first few hundred miles, or at the initial gear oil service interval, the lubricant may appear darkened by the worn-off coating. It will contain trace ferrous particles from the n
full bulletin at NHTSA ↗Noise, Vibration, and Harshness (NVH) Diagnostic Guidelines Diagnostic Guidelines When diagnosing NVH concerns, it is essential to first classify the issue into one of three primary categories: Noise, Vibration, or Harshness. Many customer complaints may involve overlapping symptoms, such as both noise and vibration, so identifying the dominant characteristic is critical. Once the primary symptom is determined, follow the appropriate diagnostic path. For example, if a concern includes both noise and vibration but is related to vehicle speed, the vibration diagnostic path should be followed. When considering component replacement during the diagnostic process, it is best practice to start wit
full bulletin at NHTSA ↗Some customer's might state that they notice fluid or oil leaking/dripping on the ground when the vehicle is parked. For this concern, inspect the vehicle for any trace of a fluid or oil leak and use the following examples as a guide to determine if it is severe enough to require a repair, or just to clean the area and monitor it at the next service. Examples of residue or seepage that may not be considered a leak and that may not require repair based on splash shield inspection.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Ten of the twelve narratives describe the same failure: the 2018 CX-9 cylinder head cracks and leaks coolant, typically around the exhaust manifold. Owners spotted leaks by watching coolant pool under the car or hearing a sloshing sound at startup. Several caught the problem early; others found it only because coolant ran dry. Critical issue: most owners report receiving no warning lights—no check-engine, no high-coolant, no overheat alert—leaving drivers unaware until damage is done.
Owners cite Mazda Technical Service Bulletins 01-002/23 and 01-013/21, which document exhaust manifold deformation and casting stress as root causes. Mazda introduced Customer Service Program CSP11, extending powertrain warranty to 10 years/120,000 miles for cylinder head coolant leaks. However, one owner at 88,000 miles had the repair capped by CSP11 while the crack spread to the exhaust manifold and cracked the turbocharger—secondary failures CSP11 does not cover.
One owner paid $7,000 for cylinder head resurfacing and gasket replacement, only to find the leak persist; full engine replacement now needed. Owners past the extended warranty window report dealers refusing coverage outright. A separate narrative describes a forward-sensing camera malfunction unrelated to the cooling defect.
Failure modes owners describe
Cracked cylinder head with coolant leak
Cylinder head develops cracks, typically around the exhaust manifold area, allowing coolant to escape. Owners report detection by visible coolant dripping from the powertrain to the floor or a liquid slushing sound after starting. The crack is linked by owners to exhaust manifold deformation and residual production stress documented in Mazda technical bulletins.
When: 53,300 to 88,000 miles reported; one owner noted failure after powertrain warranty expired
Symptoms owners cite: Visible coolant leaking from powertrain to floor; Liquid slushing sound after engine start; Engine not shutting off immediately when turned off; Fan running at high speed; Engine check light illumination
Repairs/costs cited: One owner reported $7,000 cost for cylinder head resurfacing and gasket replacement; repair did not resolve issue and full engine replacement anticipated. Dealers refusing coverage after powertrain warranty expiration.
Recalls/TSBs owners mention: TSB 01-002/23 (also referenced as 01-013/21 and 01-01321 in narratives); Mazda Customer Service Program CSP11 extends powertrain warranty to 10 years/120,000 miles for coolant leaks at cylinder head but does not cover consequential damage to exhaust manifold and turbocharger; dealers refusing claims post-warranty
Cracked exhaust manifold
Exhaust manifold cracks develop, identified by owners as resulting from design defect and deformation. Damage occurs in high-stress zone directly mounted to the cylinder head. One owner noted a broken catalyst due to high temperature caused by the manifold failure.
When: Concurrent with or following cylinder head failure; at 88,000 miles in one documented case
Symptoms owners cite: Broken catalytic converter due to high temperature exposure; No high-temperature warning lamp displayed despite failure
Repairs/costs cited: One owner noted catalyst removal revealed catalyst breakage; full repair cost not stated separately
Recalls/TSBs owners mention: TSB 01-002/23 identifies exhaust manifold deformation and residual production stress as root causes; CSP11 does not address exhaust manifold repair
Cracked turbocharger
Turbocharger housing cracks, occurring in coolant-cooled turbo units mounted directly to the cylinder head in high-stress zone. Owners report this as a secondary failure resulting from coolant loss due to cylinder head cracking; as coolant supply is depleted, turbocharger lacks cooling and overheats, leading to housing crack.
When: Following cylinder head failure; at 88,000 miles in one documented case
Symptoms owners cite: Turbocharger cracking secondary to cylinder head coolant loss
Repairs/costs cited: Not explicitly stated; turbocharger replacement anticipated as part of engine rebuild
Recalls/TSBs owners mention: TSB 01-002/23 documents the defect; CSP11 does not cover turbocharger repair as consequential damage
Forward sensing camera malfunction (unrelated safety system)
Forward sensing camera stops functioning, triggering multiple dashboard warning lights. Owners report rough engine running and acceleration issues coinciding with light illumination. This failure is distinct from powertrain cooling system issues.
When: Timing not specified in narrative
Symptoms owners cite: Forward sensing camera malfunction; Forward smart city brake support warning light; Smart brake system warning light; Front camera sensor malfunction warning light; Engine running rough; Acceleration issues
Codes mentioned: SCBS/SBS, LAS/LDWS, MASTER and/or HBC warning lights
Synthesized from 12 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 1 most recent
At 102,000 miles I have a cracked cylinder head
Had powertrain trouble with your 2018 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 powertrain problem on the 2018 Mazda CX-9?
It's a documented issue but not catastrophic. 12 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain 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 $2,500 for powertrain 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 powertrain?
No active recalls currently cover powertrain 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/2018/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.