Mazda Skyactiv-G Engine (2.0 & 2.5)
Skyactiv-G is the petrol engine in every modern Mazda — Mazda3, Mazda6, CX-5, CX-30, CX-50, CX-9 and MX-5. It is efficient and generally well built. But the 2018-onward 2.5 has one serious failure, and before you spend anything on a replacement there are two Mazda warranty extensions worth checking, because one of them runs for fifteen years.
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Mazda extended the warranty on two of these faults, and both windows are long. If your car qualifies, the repair may cost you nothing. Call a dealer with your VIN before buying an engine — we would rather lose the sale than sell you something you did not need.
| Campaign | Covers | Extended to |
|---|---|---|
| CSP 11 | Cracked cylinder head, on some models | 10 years / 120,000 miles |
| SSPD8 | Coolant Control Valve (CCV) | 15 years / 150,000 miles |
There are also two free recall repairs: 3719F (NHTSA 19V497000) for the cylinder deactivation software, and 5321K for the low-pressure fuel pump on 2018–2019 CX-5.
Always confirm which campaigns apply to your specific VIN with a Mazda dealer — coverage varies by model and build.
The cracked cylinder head
This is the serious one on the 2018–2024 2.5, and Mazda addressed it in TSB 01-002/23.
The head cracks, and the symptoms are external oil or coolant leaks near the exhaust manifold. Left alone it progresses to coolant mixing with the oil, which is the point at which the engine is finished.
It is frequently misdiagnosed as oil consumption. Owners report excessive oil use, an oil smell or low-oil warnings, and the cause turns out to be a cracked head. If a 2018-onward 2.5 is using oil, check for leaks around the exhaust manifold before assuming rings.
Mazda redesigned the head and gaskets. If you are buying a used 2.5 from this era, ask whether the donor engine had the revised head — and if it was replaced under CSP 11, that is a good engine, not a suspect one.
Cylinder deactivation: what it added
Mazda added cylinder deactivation to the 2.5 in 2018 for fuel economy. It brought its own problems.
- Stalling or misfires when the engine switches between two and four cylinders.
- Rocker arm slip. On 2018–2019 models a software bug could cause a rocker arm to slip, with at least one documented case of a rocker arm coming off cylinder 4. Recall 3719F covers this with a free PCM software update — it applies to 2018–2019 CX-5 and Mazda6, and 2019 Mazda3.
- Low-pressure fuel pump on 2018–2019 CX-5, covered by recall 5321K, which can also cause stalling.
If you are fitting a used 2018-onward 2.5, make sure the PCM software is current. The hardware alone is not the fix.
Other known issues
| Issue | Reference | Years |
|---|---|---|
| Hydraulic lash adjuster ticking | TSB SA-012/19 | 2018–2021 |
| Front cover oil leak | TSB SA-013/23 — reseal with Mazda’s specified liquid sealant | 2018–2023 |
| Coolant Control Valve, code P0126:00 | SSPD8 — thermostat stuck open, slow warm-up | CX-5, Mazda6, CX-50 |
| Intake valve carbon buildup | No TSB — inherent to direct injection | All |
About the carbon
Every direct-injected engine builds carbon on the intake valves, because no fuel washes across the back of them. On Skyactiv-G it typically shows up between 60,000 and 100,000 miles as misfires or reduced power. Walnut blasting or chemical cleaning runs roughly $400 to $800. Treat it as maintenance, not a defect.
Skyactiv-G specifications
| 2.0 (PE-VPS) | 2.5 (PY-VPS) | 2.5T (PY-VPTS) | |
|---|---|---|---|
| Displacement | 1,998 cc | 2,488 cc | 2,488 cc |
| Bore × stroke | 83.5 × 91.2 mm | 89.0 × 100.0 mm | 89.0 × 100.0 mm |
| Compression | 13:1 (US) | 13:1 (US) | 10.5:1 |
| Output | 155 hp, 200 N·m | 187 hp, 252 N·m (191 hp from 2023) | 255 hp on premium, 227 hp on regular |
The 2.5 and the 2.5T are not the same engine. Same displacement, same bore and stroke — but 13:1 against 10.5:1 compression, plus a turbo and a different fuel system. Do not buy on litres.
How to identify your Skyactiv-G
On Mazda the engine is identified by the 8th digit of the VIN, as on most vehicles sold in the US.
Three more things decide fitment:
- Turbo or not. 2.5 versus 2.5T is the biggest trap on this platform.
- Cylinder deactivation. 2018 was the dividing line on the 2.5.
- Build cutoffs. Mazda has used mid-year production splits, and our listings carry them where the supplier recorded them — written as, for example, “thru VIN 131460”.
Text your VIN to +1 (361) 470-5276 and we will confirm the engine code, whether yours has deactivation, and everything that interchanges. Free.
Which vehicles use Skyactiv-G
| Engine | Vehicles |
|---|---|
| 2.0 | Mazda3 2012– · Mazda6 2013–2025 · CX-5 2013– · CX-3 2015– · MX-5 2016– · CX-30 2019– · Mazda5 2013–2015 |
| 2.5 | Mazda6 2013–2025 · CX-5 2013– · Mazda3 2014– · CX-30 2020– · CX-50 2023– · CX-60 2022– |
| 2.5T | CX-9 2016–2024 · CX-8 2018– · Mazda6 2018–2021 · CX-5 2019–2025 · Mazda3 2021– · CX-30 2021– · CX-50 2023– |
Browse stock: used Mazda engines.
Which to buy
- Pre-2018 2.5 engines avoid both the cracked head window and cylinder deactivation entirely. For a straightforward replacement, these are the easiest buy.
- 2018 onward, ask whether the donor had the revised head, and make sure the PCM software is current for the deactivation recall.
- An engine replaced under CSP 11 is a good thing, not a red flag — it means the revised head is already in there.
- The 2.0 is the quieter life. No deactivation, no turbo, and the cracked head issue is associated with the 2.5.
Used vs remanufactured
When used makes sense
Almost always on this platform. Skyactiv-G engines are plentiful, and a used unit from outside the problem window costs a fraction of a rebuild while keeping factory tolerances.
When remanufactured makes sense
If you are committed to a 2018-onward 2.5 and want the revised head guaranteed, a rebuild with the updated head and gaskets gives you that in writing. Ask the rebuilder specifically about the head revision, since that is the component that matters.
Used Mazda engine prices
Our Mazda engines start at $770, priced by variant and mileage. Mileage on every listing is read off the donor odometer rather than estimated, and we photograph the actual unit before it ships.
Live prices: used Mazda engines.
What is included
Engines ship as tested assemblies. You transfer your own intake, sensors, accessories and flywheel or flexplate from the old engine. Each listing states what is attached to that unit.
On a 2018-onward 2.5, budget for the PCM software update at the same time — the deactivation recall fix is software, and a new engine on old software does not solve it.
Shipping and warranty
Every engine is compression tested and photographed on the pallet before dispatch. Preparation takes 3 to 5 business days, then 2 to 4 days in transit on insured freight. Shipping is free to any address in all 50 states, residential included.
Standard warranty is 6 months, extendable to 3 years, with 7-day returns and free return shipping. Full terms: engine warranty policy · shipping policy · returns.
Frequently asked questions
What is the Mazda 2.5 cracked cylinder head problem?
On 2018 to 2024 Skyactiv-G 2.5 engines the cylinder head can crack, covered by Mazda TSB 01-002/23. Symptoms are external oil or coolant leaks near the exhaust manifold, progressing to coolant mixing with the oil. It is often misdiagnosed as oil consumption. Mazda redesigned the head and gaskets, and warranty extension CSP 11 covers the repair on some models for up to 10 years or 120,000 miles.
Is my Mazda still covered for a free repair?
Possibly. CSP 11 extends cracked cylinder head coverage to 10 years or 120,000 miles on some models, and SSPD8 extends Coolant Control Valve coverage to 15 years or 150,000 miles. Recalls 3719F and 5321K are free repairs for the cylinder deactivation software and the low-pressure fuel pump. Call a Mazda dealer with your VIN before buying an engine.
Is the 2.5 Skyactiv the same as the 2.5 turbo?
No. Both are 2,488 cc with an 89 mm bore and 100 mm stroke, but the naturally aspirated 2.5 runs 13:1 compression and the 2.5T runs 10.5:1 with a turbo and a different fuel system. They do not interchange.
Which Mazda engines have cylinder deactivation?
Mazda added it to the 2.5 in 2018. On 2018 to 2019 models a software bug could cause a rocker arm to slip, addressed free of charge under recall 3719F for 2018 to 2019 CX-5 and Mazda6 and 2019 Mazda3. Pre-2018 2.5 engines have no deactivation at all.
Why does my Skyactiv engine misfire at high mileage?
Usually intake valve carbon buildup, which is inherent to direct injection because no fuel washes across the back of the valves. It typically appears between 60,000 and 100,000 miles as misfires or reduced power. Walnut blasting or chemical cleaning costs roughly $400 to $800 and should be treated as maintenance.
What does code P0126:00 mean on a Mazda?
A failed Coolant Control Valve, with the thermostat stuck open causing slow warm-up. Mazda covers it under SSPD8 with a 15-year, 150,000-mile warranty extension, using a dummy plug and a PCM update.
Which VIN digit identifies a Mazda engine?
The 8th digit, as on most vehicles sold in the US. You also need to know whether the car is turbo or naturally aspirated, and whether it has cylinder deactivation, since those decide fitment more than the year does.
How much is a used Mazda Skyactiv engine?
Ours start at $770, priced by variant and mileage. Every unit is compression tested and photographed before dispatch, and live pricing is on the Mazda collection page.
Send your VIN. We will confirm the engine code, turbo or not, deactivation or not, and what fits.
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