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Reliability report · 2021 Mazda CX-9 · Updated July 2026 · ~$2,600/yr fuel · what it costs to keep →

The oil-consumption year — the engine story flips from coolant to oil, and this is the first year CSP11 no longer covers.

The 2021 marks a clean shift in the engine story. The loud pattern is now excessive oil consumption — owners reporting the low-oil light and needing to add roughly a quart every 2,500 to 4,000 miles — traced to defective valve stem seals on the 2.5-liter turbo (referenced in TSB 01-012/21 and a class-action suit). Mazda addressed it with SSPD5, a Special Service Program tied to a Valve Stem Seals class-action settlement that extends the engine powertrain warranty for oil consumption and reimburses some out-of-pocket oil costs; owners describe the extension as reaching 7 years/84,000 miles.

The catch: 2021 is the first year the CSP11 cylinder-head coolant-leak extension does NOT cover (CSP11 stops at 2020). A cracked head still appears occasionally in the 2021 file — one owner just outside the recall range at 87,000 miles — and on 2021 that repair is not warranty-extended. One recall applies: 21V750 (Mazda 5221I), the 2020-2021 second-row seat that can slide in a crash. This is a Chirping year: confirm SSPD5 eligibility and the oil-consumption history, and understand the head crack is uncovered here.

Evidence: 34 NHTSA complaints · 1 recall campaigns · 7 mechanic & forum sources

Canary status

Chirping

What that means: 34 federal complaints, and the mix has changed: the dominant engine issue is now excessive oil consumption from defective valve stem seals, addressed by a class-action settlement program (SSPD5), not the cracked-head coolant leak. Crucially, 2021 falls outside the CSP11 head-crack extension, so the occasional head crack that still appears here is on the owner. One seat recall applies. Verify both the oil program and any engine history.

CalmChirpingSquawkingFainted

34

Federal complaints

SSPD5

Oil-consumption settlement program

Known issues

Ranked by the cost of ignoring them. Every claim carries its source.

Excessive oil consumption — valve stem seals (SSPD5 settlement program)

major
  • 2.5L turbo (SkyActiv-G)

The signature 2021 issue and the bulk of the file. Defective valve stem seals let engine oil into the combustion chamber, so the 2.5-liter turbo burns roughly a quart every 2,500 to 4,000 miles — owners report the low-oil light before the first scheduled change. Left unmanaged it risks carbon fouling and longer-term engine damage. Mazda's SSPD5 — a Special Service Program tied to a Valve Stem Seals class-action settlement — extends the engine powertrain warranty for oil consumption and reimburses limited out-of-pocket oil costs; owners cite a 7-year/84,000-mile extension. Confirm SSPD5 eligibility and whether the seals were replaced, and check the oil level and consumption yourself between changes.

Valve-stem-seal / oil-consumption repair under SSPD5

$0 (if eligible)

Sources: NHTSA complaint database, 2021 Mazda CX-9 · NHTSA recalls + manufacturer communications (SSPD5, CSP11 window, 21V750, campaign documents) · Independent mechanic and owner/specialist channel transcripts (CX-9 second generation, 2.5T)

Cracked cylinder head — now UNCOVERED (CSP11 does not reach 2021)moderate

The cracked-cylinder-head coolant leak that dominated 2016-2018 still appears occasionally on 2021, but here it matters differently: CSP11, the coolant-leak warranty extension, only covers 2016-2020, so on a 2021 this repair is on the owner. One 2021 owner reported a cracked head at 87,000 miles, just outside the CSP11 range and denied coverage. It is far less common on 2021 than on the early years, but if it happens it is a several-thousand-dollar out-of-pocket repair. Inspect for coolant residue at the back of the block and treat any coolant loss as significant.

Sources: NHTSA complaint database, 2021 Mazda CX-9 · NHTSA recalls + manufacturer communications (SSPD5, CSP11 window, 21V750, campaign documents)

several thousand

Cylinder-head repair (uncovered on 2021)

Second-row seat recall (21V750) and driver-aid faultsmoderate

Recall 21V750 (Mazda 5221I) covers 2020-2021 CX-9s with 60/40 split second-row seats, where the left-side seat can slide forward in a crash (fails Federal Motor Vehicle Safety Standard 210); the remedy is a free replacement of internal seat parts. Separately, the i-ACTIVSENSE driver aids continue to throw false Smart Brake Support / front-radar malfunctions, sometimes with a brief power loss on the highway. Confirm the recall by VIN and test the driver aids on the drive.

Sources: NHTSA complaint database, 2021 Mazda CX-9 · NHTSA recalls + manufacturer communications (SSPD5, CSP11 window, 21V750, campaign documents)

On the 2021, the complaint that repeats is oil — a quart every 2,500-4,000 miles from bad valve stem seals — and it's the first year Mazda's cylinder-head warranty extension doesn't reach.
7 mechanic & owner sources

Open recalls

Free fixes at any Mazda dealer. Run the VIN — “completed” isn’t always completed.

  1. 21V7502020-2021 CX-9 with 60/40 split second-row bench seats: left-side second-row seat may slide forward in a crash (fails FMVSS 210). Free replacement of internal seat parts; letters mailed November 4, 2021. Mazda code 5221I.open

What it costs to keep

The purchase price is what you negotiate. These are the numbers you live with afterward — each one sourced, none of them blended into a fake total.

The ownership picture — 2021 CX-9

Four sourced numbers. No fake total.

Fuel

24 MPG combined (22 city / 28 highway) for the FWD, 2.5L turbo on the EPA federal fuel-economy test.

Source: FuelEconomy.gov (EPA) — EPA’s federal fuel-economy test, recomputed with current gas prices. EPA record 43127 (CX-9 2WD).
Other builds EPA lists: 4WD, 2.5L turbo 23 MPG.

$2,600/yr

at $4.15/gal · 15,000 mi/yr · 55/45 city/hwy · pulled Jul 12, 2026

Crash losses

Collision losses run about average here. Neither a red flag nor a discount at the insurer.

Source: HLDI — the insurance industry’s loss-data institute — HLDI collision losses, 2020–22 models, published April 2023 (report R-23). 100 = the all-vehicle average. Series read: Mazda CX-9 4dr 4WD.

102 vs 100

2% above average

Theft

Stolen about 71% less often than the average vehicle. One less thing to price into coverage.

Source: HLDI — HLDI whole vehicle theft losses, 2020–22 models, published April 2023 (report WT-22). 100 = the all-vehicle average. Series read: Mazda CX-9 4dr 4WD.

29 vs 100

71% below average

Repair risk

What this specific year is known to need. Pulled from the issues above — the repairs owners actually report, at the costs they report them. Averages from other sites blend every year together; these are this year’s own numbers.

Source: this report — 01 Known issues.

Valve-stem-seal / oil-consumption repair under SSPD5$0 (if eligible)
Cylinder-head repair (uncovered on 2021)several thousand
Why there’s no single “cost to own” number: sites that promise one are guessing at your insurance quote, your annual miles, and your luck. These are the numbers we can actually source — and each one carries its receipt.

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The VIN is on the listing. We’ll check this exact car — build, open recalls, and whether the “completed” repairs stayed fixed.

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Before you buy

Print this
  1. 01Check oil level and consumption between changes — excessive oil burn from valve stem seals is this year's defining issue.
  2. 02Confirm SSPD5 (valve-stem-seal / oil-consumption settlement extension) eligibility and whether the seals were already replaced.
  3. 03Understand the cracked-head coolant leak is NOT covered on 2021 (CSP11 stops at 2020) — treat any coolant loss at the back of the engine as a costly, owner-pay risk.
  4. 04Run the VIN against recall 21V750 (second-row seat) and confirm completed.
  5. 05Test the automatic Smart Brake Support, front radar, and adaptive cruise for false activation.
  6. 06Get engine repair and oil-service history in writing.

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