A lot of engine oil consuption, 1 quart per 2500 miles.
2021 Mazda CX-9 engine problems
moderate 15 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
15
Recalls
0
Avg fix
$3,100
What stands out
No new NHTSA engine complaint has been filed on this vehicle in over 3 years — the issue may be aging out of the active population.
The failure pattern owners describe
Buyer takeaway: A 2021 CX-9 can burn through oil unusually fast—1–2 quarts every 3,000–3,500 miles—with the low-oil light coming on early and repeatedly. While Mazda has acknowledged the problem in technical bulletins, no recall exists, and owners report the issue persists even after dealership repairs.
Fifteen complaints converge on one dominant issue: excessive oil consumption in the 2021 Mazda CX-9. Owners describe losing 1–2 quarts of oil every 3,000–3,500 miles—far faster than normal—with the low-oil warning light triggering well before the next scheduled oil change. A brand-new vehicle burned oil between its first and second oil-change intervals; another owner added a quart after just 2,300 miles of driving. These aren't isolated incidents: owners cite Mazda's own technical service bulletins (MT-005/20, TSB #01-012/21) admitting the problem is widespread and "known," while a class-action lawsuit points to defective valve stem seals as the root cause.
Dealerships have confirmed the diagnosis and performed valve stem seal replacements, though some owners report oil loss continues after the repair. One complaint also describes loss of motive power and stalling at highway speeds around 49,000 miles, with the driver requiring multiple restart attempts to restore function—a potential safety issue owners link to oil-related engine degradation.
No manufacturer recall has been issued despite the bulletins confirming a defect pattern.
Same Mazda CX-9 engine reports on nearby years: 2018 · 2019
Failure modes owners describe
Excessive Oil Consumption
Engine burns or leaks oil at an abnormal rate between scheduled oil changes, typically consuming 1–2+ quarts in intervals of 3,000–3,500 miles. Owners report the low-oil warning light activating well before the next scheduled maintenance.
When: Typically 1,000–3,000 miles after oil change; some reports by 2,000–3,000 miles on new vehicles
Symptoms owners cite: Low oil warning light illuminates; Oil level drops to add mark or low reading when checked; Requires topping off oil every 3,000–3,500 miles; Oil loss observed after partial refills on subsequent checks
Repairs/costs cited: Mazda dealership replaced defective valve stem seals per service bulletin; some owners report ongoing oil loss despite seal repair
Recalls/TSBs owners mention: Mazda technical service bulletin MT-005/20 and TSB #01-012/21 acknowledge excessive oil consumption as a known issue. No manufacturer recall issued as of complaint dates. Defective valve stem seals identified as root cause in service bulletins and in class-action lawsuit filings.
Stalling and Loss of Motive Power
Engine loses power and stalls while driving at highway speeds without warning. Vehicle must be coasted to the roadside and restarted multiple times to regain normal function.
When: Approximately 49,000 miles
Symptoms owners cite: Loss of motive power while driving at or exceeding 60 mph; Vehicle stalls without warning; Requires 2–3 restart attempts to regain normal functionality
Synthesized from 15 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 7 most recent
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…
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…
Car loses oil and coolant rapidly
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.
Had engine trouble with your 2021 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 2021 Mazda CX-9?
It's a documented issue but not catastrophic. 15 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?
Based on the 15 complaints filed, engine issues most often appear around 49,000 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
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/2021/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.