2018 Mazda Mazda6 Problems: 6 Known Issues
2018 model year · 2,600+ owner reports · Updated October 2026
According to Au7o's analysis of 2,600+ owner reports, the 2018 Mazda Mazda6 has 6 documented known issues, with 3 rated critical. The most serious are Variable Valve Timing (VVT) Actuator Failure ($400-$1,200 repair), SkyActiv-G 2.5T Turbo Cylinder Head Cracking / Coolant Leak ($2,000-$6,000 repair) and Low-Pressure Fuel Pump Impeller Cracking / Engine Stall (Recall 21V875 / 5321K). The most commonly reported issue is Variable Valve Timing (VVT) Actuator Failure with 1,400 owner reports. Across all issues with published estimates, repair costs range from $200 to $6,000. DIY maintenance guides at au7o.io.
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All 6 Known Issues
NHTSA Recalls3 recalls
FUEL SYSTEM, GASOLINE:DELIVERY:FUEL PUMP
Mazda North American Operations (Mazda) is recalling certain 2018 Mazda3, Mazda6, 2019 CX-3, 2018-2019 MX-5, CX-5, CX-9, and 2019-2020 Mazda2 vehicles. The impeller inside the low-pressure fuel pump may crack and deform, potentially causing the fuel pump to fail.
ENGINE
Mazda North American Operations (Mazda) is recalling certain 2018-2019 CX-5, Mazda6, and 2019 Mazda3 vehicles. A software error in the powertrain control module (PCM) may cause the engine to stall.
EXTERIOR LIGHTING:TURN SIGNAL
Mazda North American Operations (Mazda) is recalling certain model year 2017 Mazda6 vehicles manufactured August 12, 2016, to September 28, 2016 and equipped with optional accessory fog lights. Due to an incorrect combination switch being installed, the turn signals may not automatically cancel by the rotation of the steering wheel. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 108, "Lamps, Reflective Devices, and Associated Equipment."
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Frequently Asked Questions
What are the most common Mazda Mazda6 problems?
According to Au7o's analysis of 2,600+ owner reports, the 2018 Mazda Mazda6 has 6 documented issues. The most frequently reported are: Variable Valve Timing (VVT) Actuator Failure, SkyActiv-G 2.5T Turbo Cylinder Head Cracking / Coolant Leak, Low-Pressure Fuel Pump Impeller Cracking / Engine Stall (Recall 21V875 / 5321K). Of these, 3 are rated critical and should be addressed promptly.
Is the Mazda Mazda6 reliable?
The 2018 Mazda Mazda6 has 6 known issues documented across 2,600+ owner reports. 3 issues are rated critical: Variable Valve Timing (VVT) Actuator Failure and SkyActiv-G 2.5T Turbo Cylinder Head Cracking / Coolant Leak and Low-Pressure Fuel Pump Impeller Cracking / Engine Stall (Recall 21V875 / 5321K). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
How much does it cost to fix common Mazda Mazda6 problems?
Repair costs for known Mazda Mazda6 issues range from $200 to $6,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Variable Valve Timing (VVT) Actuator Failure, typically costs $400-$1,200 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What is the 2009-2021 Mazda Mazda6 Variable Valve Timing (VVT) Actuator Failure?
The intake-side VVT actuator (cam phaser) fails due to oil sludge and wear, causing timing codes and engine rattle. The actuator solenoid can also stick, leading to incorrect valve timing. Oil change neglect accelerates failure. Common on both MZR and early SkyActiv 2.5L engines. Repairs typically run $400-$1,200. Severity: high.
What is the 2018-2020 Mazda Mazda6 SkyActiv-G 2.5T Turbo Cylinder Head Cracking / Coolant Leak?
A proposed class action alleges that the turbocharged SKYACTIV-G 2.5T engine in 2018-2020 Mazda6 (and other Mazda models) has a structural weakness in the cylinder head near the exhaust manifold. Cracks can develop at the stud bolt hole or the outside of the exhaust manifold, all… Repairs typically run $2,000-$6,000. Severity: high.
What is the 2018 Mazda Mazda6 Low-Pressure Fuel Pump Impeller Cracking / Engine Stall (Recall 21V875 / 5321K)?
Recall 5321K / NHTSA 21V875 covers certain 2018 Mazda6 vehicles built with the subject low-pressure fuel pump. An inadequately dense impeller can develop surface cracking, deform and interfere with the pump body, causing fuel-pump failure, no-start or an engine stall. Severity: high.
What is the 2009-2021 Mazda Mazda6 Rear Brake Caliper Seizing?
Rear brake calipers seize due to corrosion of slide pins and the integrated parking brake mechanism. Salt-belt vehicles are especially affected. Causes dragging brakes, uneven pad wear, and premature rotor warping. The parking brake cable can also corrode and prevent full caliper… Repairs typically run $250-$650. Severity: medium.
What is the 2014-2021 Mazda Mazda6 Mazda Connect Infotainment Freezing / Reboot Loop?
Mazda communications document multiple distinct infotainment paths: 2014 navigation freezes, 2016 software-correctable black-screen/freezing/reboot concerns, a narrow 2016 CMU hardware shutdown, and diagnostic guidance through 2021. CSP13 provides a 24-month limited warranty exte… Severity: medium.
What is the 2018 Mazda Mazda6 EGR Valve Carbon Buildup (SkyActiv-G 2.5T)?
The SkyActiv-G 2.5T turbo engine in 2018 Mazda6 models can accumulate carbon at the EGR valve. The EGR valve accumulates carbon deposits over time; deposits pinched at the valve seat keep the valve from closing fully, and because the valve has no position sensor its closed positi… Repairs typically run $200-$800. Severity: medium.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.