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Mazda · Known Issues

2021 Mazda Mazda6 Problems: 6 Known Issues

2021 model year · 2,600+ owner reports · Updated September 2026

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Issue summary

According to Au7o's analysis of 2,600+ owner reports, the 2021 Mazda Mazda6 has 6 documented known issues, with 2 rated critical. The most serious are Variable Valve Timing (VVT) Actuator Failure ($400-$1,200 repair) and SkyActiv-G 2.5T Turbo Cylinder Head Cracking / Coolant Leak ($2,000-$6,000 repair). 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.

In This Article

  • Mazda6 Engine4
  • Mazda6 Brakes1
  • Mazda6 Electrical1
  • Recalls3
  • FAQ
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In This Article

  • Engine4
  • Brakes1
  • Electrical1
  • Recalls3
  • FAQ

All 6 Known Issues

Filter:
ALL YEARS2021202020192018201720162015201420132012201120102009200820072006200520042003
Community reported
1,400 owners

On the 2009-2021 Mazda Mazda6, the exhaust-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.

Common Symptoms

  • Rattling noise on cold start (chain slap)
  • Check engine light with P0012 or P0022 cam timing codes
  • Rough idle and stalling at stop lights
  • Reduced power and poor fuel economy

How to Fix

Replace VVT actuator/cam phaser assembly and VVT solenoid. Use Mazda-spec 0W-20 full synthetic oil and replace at 5,000-mile intervals to prevent sludge. Check timing chain stretch while servicing.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Mazda genuine electric intake VVT actuator PE01-12-4X0B
    OEMMazda PE01-12-4X0B

    Electric intake VVT actuator after the bulletin PID test confirms actuator failure Fitment/availability: The inspected direct page identifies genuine Mazda PE01-12-4X0B as the actuator and lists 2014-2017 Mazda6 2.5L applications.

    MazdaPartsNow

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipUse full synthetic 0W-20 (Mazda spec) and change oil every 5,000 miles max - Mazda6Club.com VVT thread
  • TipInspect timing chain stretch when replacing VVT - may need chain replacement at high mileage
Typical repair cost:$400 - $1,200

Research This Issue

Based on 1,400 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerified1,400 owner reportsLast reported by owners Aug 2024Reviewed Feb 2026

On the 2018-2021 Mazda Mazda6, a proposed class action alleges that the turbocharged SKYACTIV-G 2.5T engine in 2018-2021 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, allowing coolant to leak externally or into the cylinders. Loss of coolant leads to overheating and, in severe cases, catastrophic engine failure. Mazda has acknowledged the issue through TSBs but has not issued a recall.

Common Symptoms

  • Unexplained coolant loss
  • White exhaust smoke or sweet coolant smell
  • Engine overheating
  • Low coolant warning
  • Coolant mixing with oil

How to Fix

Repair typically requires replacement of the cracked cylinder head and related coolant system service; some owners pursue reimbursement through the class action or goodwill assistance. Monitor coolant level and address overheating immediately to prevent engine destruction.

Typical repair cost:$2,000 - $6,000

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerifiedReviewed Jun 2026

On the 2014-2021 Mazda Mazda6, because the SkyActiv-G direct-injection engine sprays fuel directly into the cylinder, no detergent fuel ever washes the back of the intake valves. Oil vapor drawn through the PCV system bakes onto the hot valve stems and accumulates as hard carbon, typically becoming noticeable on the 2.5L between 60,000 and 100,000 miles. The deposits restrict airflow and cause rough idle and cold-start misfires that are otherwise hard to diagnose.

Common Symptoms

  • Rough idle
  • Cold-start misfire or hesitation
  • Reduced power and fuel economy
  • Random/cylinder-specific misfire codes

How to Fix

Walnut-shell blasting of the intake valves is the standard fix, restoring throttle response and reducing misfires. Using quality oil, an oil catch can, periodic Italian tune-ups, and top-engine cleaners can slow reaccumulation.

Typical repair cost:$300 - $600

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerifiedReviewed Jun 2026

On the 2014-2021 Mazda Mazda6 SkyActiv 2.5L, the SkyActiv 2.5L engine in third-generation Mazda6 models uses a cooled EGR system that is prone to carbon buildup and coolant leaks. The EGR valve and cooler accumulate carbon deposits over time, restricting flow and causing rough idle and reduced performance. Additionally, the EGR cooler gaskets can leak coolant into the intake or externally, creating a potential overheating risk.

Common Symptoms

  • Rough idle
  • Check engine light
  • Coolant smell from engine bay
  • Reduced power and hesitation
  • Slow coolant level drop

How to Fix

Remove and clean the EGR valve and passages with carburetor cleaner and a wire brush. Replace the EGR cooler gaskets. If the EGR valve is stuck or damaged, replace it. Mazda issued TSB 01-018/17 for EGR-related issues. Use top-tier fuel and consider an occasional Italian tune-up (sustained highway driving) to help reduce carbon buildup.

Typical repair cost:$200 - $800

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
Medium Confidence
Community reported
1,200 owners

On the 2009-2021 Mazda Mazda6, 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 release.

Common Symptoms

  • Rear brake dragging and heat buildup
  • Uneven rear pad wear (inner pad worn significantly more)
  • Vehicle pulls to one side during braking
  • Burning brake smell after short drives

How to Fix

Replace or rebuild rear calipers, replace slide pins, and lubricate with silicone-based brake grease. Replace parking brake cables if corroded. Annual brake maintenance prevents recurrence.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Centric remanufactured rear driver-side brake caliper 141.61556
    OEMCentric 141.61556

    Left/driver rear caliper after hydraulic and mechanical tests prove the caliper piston or parking-brake actuator is seized or leaking Fitment/availability: The inspected direct page identifies Centric 141.61556 as a semi-loaded rear driv…

    Auto Parts Prime
  • Centric remanufactured rear passenger-side brake caliper 141.61555
    OEMCentric 141.61555

    Right/passenger rear caliper after hydraulic and mechanical tests prove the caliper piston or parking-brake actuator is seized or leaking Fitment/availability: The inspected direct page identifies Centric 141.61555 as a semi-loaded rear …

    Auto Parts Prime

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipService rear brakes annually - clean and lube slide pins with CRC Silaramic brake grease
  • TipEngage parking brake daily to keep cable from seizing - Mazda6Club.com brakes forum
Typical repair cost:$250 - $650

Research This Issue

Based on 1,200 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerified1,200 owner reportsLast reported by owners Sep 2024Reviewed Feb 2026

On the 2014-2021 Mazda Mazda6, 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 extension for software updates and/or necessary CMU repair or replacement only on eligible 2016-2021 Mazda6 vehicles with CSP13 shown in Warranty Vehicle Inquiry; it does not cover every screen, switch, SD card, reader or wiring concern.

Common Symptoms

  • screen freezes, goes black or reboots
  • system shuts down and only recovers after an ignition cycle
  • USB, SD, navigation or favorites concern may require software or component-specific diagnosis

How to Fix

Record the exact display behavior and current software version, then use Mazda's symptom troubleshooting before replacing hardware. Ask a Mazda dealer to check Warranty Vehicle Inquiry for CSP13 eligibility on 2016-2021 vehicles. Do not buy a CMU, display or SD card from this page; software, hardware and peripheral faults require different remedies and current VIN-specific parts.

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerifiedReviewed Aug 2026
NHTSA Recalls3 recalls

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."

Campaign #16V75300018/10/2016

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.

Campaign #19V49700027/06/2019

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.

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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 2021 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, Rear Brake Caliper Seizing. Of these, 2 are rated critical and should be addressed promptly.

Is the Mazda Mazda6 reliable?

The 2021 Mazda Mazda6 has 6 known issues documented across 2,600+ owner reports. 2 issues are rated critical: Variable Valve Timing (VVT) Actuator Failure and SkyActiv-G 2.5T Turbo Cylinder Head Cracking / Coolant Leak. 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 exhaust-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 2018-2021 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 2018-2021 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.

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.

Data sourced from 2,600+ owner reports, NHTSA recalls, TSBs, and automotive forums.

Campaign #21V87500012/11/2021

Enter your VIN at NHTSA.gov to check recalls specific to your vehicle.

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 SkyActiv-G Intake Valve Carbon Buildup (Direct Injection)?

Because the SkyActiv-G direct-injection engine sprays fuel directly into the cylinder, no detergent fuel ever washes the back of the intake valves. Oil vapor drawn through the PCV system bakes onto the hot valve stems and accumulates as hard carbon, typically becoming noticeable… Repairs typically run $300-$600. 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 2014-2021 Mazda Mazda6 EGR Valve Carbon Buildup and Coolant Leak (SkyActiv 2.5L)?

The SkyActiv 2.5L engine in third-generation Mazda6 models uses a cooled EGR system that is prone to carbon buildup and coolant leaks. The EGR valve and cooler accumulate carbon deposits over time, restricting flow and causing rough idle and reduced performance. Additionally, the… Repairs typically run $200-$800. Severity: medium.