The contact owns a 2021 Mazda Mazda3. The contact received notification of an unknown Class Action Lawsuit Number however, the part to do the repair was unavailable. The contact stated that the manufacturer exceeded a reasonable amount of time for the repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.
2021 Mazda Mazda3 engine problems
moderate 16 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
16
Recalls
0
Avg fix
$3,100
What stands out
Engine accounts for 33% of every owner complaint on file for this vehicle — the dominant problem area across 5 categories tracked.
Among the 13 model years of Mazda Mazda3 in our records for engine problems, this one ranks #3 by owner-complaint volume.
The failure pattern owners describe
Buyer takeaway: The 2021 Mazda3, especially the 2.5T variant, has a well-documented excessive oil-consumption issue affecting cars early in ownership with no permanent factory fix available—only topping off oil between services. A thermostat failure and cylinder misfire have also been reported.
Excessive oil consumption dominates the complaint cluster. Owners with 11,000–24,000 miles report the low oil warning appearing as early as 2,000–5,000 miles after purchase or the last service, with 1–3+ quarts consumed between intervals. Multiple owners note the problem begins day one and is particularly common on the 2.5T model. Dealerships confirm no external leaks but offer no permanent repair; Mazda has issued a TSB on the issue, though it prescribes only continued topping-off of oil as a workaround. One complaint references a class-action lawsuit, with repair parts unavailable or delayed.
One owner describes a thermostat stuck open, allowing continuous excess coolant flow, causing jolting, stuttering, failed temperature regulation, and internal engine damage—with no warning until failure occurred.
A single complaint reports cylinder misfire (code P0304) with spontaneous power loss on the highway, speed limiting, and idle vibration at cold start.
All owners agree: no permanent fix exists for the oil-consumption issue, and the burden falls on owners to maintain higher oil levels indefinitely.
Failure modes owners describe
Excessive Oil Consumption
Engine burns oil at an abnormal rate, triggering low oil warnings well before scheduled maintenance intervals. Owners report losing 1–3+ quarts between 5,000-mile service intervals on vehicles with less than 25,000 miles. Dealerships confirm no external leaks, yet the problem persists from early ownership. Multiple owners note the issue occurs from day one and is widespread across the 2.5T variant.
When: Typically 2,000–5,000 miles after purchase or previous service
Symptoms owners cite: Low engine oil warning light illuminates prematurely; Dipstick shows oil below minimum level; Oil consumed at 1–3+ quarts per service interval; Problem present from initial ownership
Repairs/costs cited: Dealers confirm no oil leaks but offer no permanent fix; temporary measure is to top off oil between services. Some dealers overfill the engine as compensation.
Recalls/TSBs owners mention: Mazda TSB issued for excessive oil consumption on affected 2.5T models; however, TSB prescribes only continued top-offs with no root-cause repair. Class action lawsuit number referenced in one complaint; parts for repair unavailable or delayed.
Thermostat Malfunction
Thermostat stuck in open position, allowing excess coolant to flow continuously and preventing proper engine temperature regulation. Caused internal engine damage, reduced fuel economy, increased emissions, and compromised engine life. No prior warning before sudden failure.
When: Mileage not specified; failure detected during normal vehicle operation
Symptoms owners cite: Thermostat remains open; Temperature gauge fails to rise to optimal range; Engine jolting and stuttering sounds; No check-engine warning prior to failure; Delayed throttle response due to improper engine temperature; Internal engine component damage
Repairs/costs cited: Vehicle available for dealership inspection; independent mechanic inspection completed.
Cylinder Misfire (Code P0304)
Engine cylinder misfires intermittently, causing loss of power and vibration at idle. Check-engine light illuminates and vehicle imposes speed limiter. One complaint cites this code appearing after spontaneous power loss on highway.
When: Mileage not specified
Symptoms owners cite: Spontaneous loss of power while driving on highway; Check-engine light illuminated; Vehicle speed limited by computer; Engine vibration at idle, especially cold start; Code P0304 appears intermittently
Codes mentioned: P0304
Synthesized from 16 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 8 most recent
Purchased car in January 2020 and within a month/few thousand miles the low engine oil light came on. Almost two years later car continues to burn excessive oil triggering low engine oil light. Dealer doesn’t acknowledge an issue, Mazda still doesn’t have a repair. Owners required to pay for excess servicing until a repair is issued. This is a widespread problem impacting the engine.
Turbo using/burning oil- Consumption issue.
Oil light has come one twice within 17,000 miles of owner ship. The first time at 4,800 miles and the second at 17,529 miles, the most recent was only 3,500 miles since the last oil change.
Low oil light - car is burning oil and only has 11,400 miles. Approx 3/4 to 1 quart missing...
After roughly 2,000 miles of driving, the low oil light comes on. The engine is burning oil. Mazda has issued a TSB on it, but they have taken no action to fix the issue. Right now they just top off the oil.
The engine is burning oil. Oil and filter were changed at 5000 miles. At about 9000 miles, the engine oil level light came on. Topped off with oil and took to dealer, they confirmed no oil leaks and changed the oil.
At around 3600 Miles my Mazda which I had for only a couple of months displayed a low engine oil light which required a visit to the dealership.This was under normal driving conditions.
Had engine trouble with your 2021 Mazda Mazda3?
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 Mazda3?
It's a documented issue but not catastrophic. 16 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/2021/Mazda/Mazda3.
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.