2018 Mazda CX-5

The contact owns a 2018 Mazda CX-5. The contact stated that while his wife was driving at an undisclosed speed, there was smoke coming from under the hood. No warning light was illuminated. The contact's wife pulled over and discovered that there was oil leaking onto the ground. The vehicle was towed to the dealer, who determined that the #5 and #7 cylinder heads were cracked and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 100,000.

NHTSA ID

11752421

Incident

Jun 23, 2026

Mileage

100,000 mi

I am writing to formally document a significant engine failure on my 2018 Mazda CX-5 Grand Touring (VIN: [XXX], License: [XXX], Odometer: 78,159 miles). The vehicle began exhibiting visible smoke from under the hood and severe oil leakage — oil was actively pooling beneath the car and leaving a trail. Upon inspection by Cal West Auto Center (San Marcos, CA), the vehicle was diagnosed with a leaking cylinder head gasket requiring full cylinder head removal and replacement. I am aware that Mazda issued Technical Service Bulletin TSB #SA-031-21 specifically addressing a cylinder head casting defect in 2018–2019 CX-5 models equipped with the 2.5L Skyactiv-G engine with cylinder deactivation — the exact configuration of my vehicle. This is a documented manufacturing defect, not normal wear and tear, and the repair estimate I have received is $4,800.84. Given that this failure is tied to a known defect acknowledged by Mazda, I am requesting that Mazda Motor America cover the cost of this repair in full, or provide a clear explanation of what goodwill or warranty coverage is available to me. I am happy to provide the repair estimate, vehicle documentation, and any additional information needed to process this request promptly. Thank you for your attention to this matter. I look forward to your response. [XXX] Cell: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11752039

Incident

Jul 1, 2025

Check engine light on when read it comes back with P0171 code

NHTSA ID

11750286

Incident

Jul 14, 2026

The contact owns a 2018 Mazda CX-5. The contact stated that white smoke was coming from the engine compartment whenever the vehicle reached normal operating temperature. The contact stated that smoke entered the passenger’s side compartment through the air vents and was coming from underneath the hood. The contact stated that there was a burning odor coming from the engine compartment due to an oil leakage. The smoke impaired visibility while driving. The most recent failure had occurred while driving approximately 35 MPH on a city roadway. The vehicle was driven to an independent mechanic to be diagnosed, and then to the dealer for further inspection. The independent mechanic diagnosed the vehicle with a cracked cylinder head and recommended that the vehicle be taken to the dealer for additional diagnostic tests. The dealer diagnosed the cylinder head as porous and informed the contact that the cylinder head needed to be replaced. The manufacturer was notified and informed the contact that the repair would not be covered. The vehicle was not repaired. The contact stated that the failure had occurred intermittently and became more frequent and severe during hotter weather. The failure mileage was approximately 83,000.

NHTSA ID

11747961

Incident

Jul 1, 2026

Mileage

83,000 mi

My Mazda 2018, CX-5, Grand Touring, was diagnosed with a cracked cylinder head at 64,599 miles. This issue could posed a safety hazard for not only us but others on the road by: *Engine Failure / Sudden Loss of Power-A crack allows coolant and oil to mix or leak, leading to overheating and potential catastrophic engine seizure. A seized engine can cause sudden, unexpected loss of power — especially dangerous at highway speeds or during lane changes/merges. *Oil and Coolant on the Road-Leaking fluids drip onto the roadway, creating slick surfaces for motorcyclists and other vehicles — similar to a spilled oil hazard. This is especially dangerous on curves and in wet conditions. *White Smoke / Steam Billowing from Exhaust-When coolant enters the combustion chamber, it burns off as thick white smoke. This can instantly reduce visibility for drivers behind the vehicle, potentially causing rear-end collisions. *Fire Risk-If oil leaks onto hot exhaust manifolds or engine components, it can ignite. An engine fire can spread quickly and, in traffic, puts surrounding vehicles and occupants at risk. *Debris from Engine Destruction-In extreme cases, a severely overheated or seized engine can cause internal components to fail violently. Debris from a catastrophic engine failure can damage undercarriages of nearby vehicles or become road hazards. *Stalling in High-Risk Locations-A vehicle that stalls due to engine failure in a tunnel, on a freeway on-ramp, in an intersection, or on a bridge creates an immediate collision risk for surrounding traffic. This is part of why Mazda's handling of the cylinder head defect is so problematic — it's not merely a costly repair, it's a public safety issue that arguably warrants regulatory attention (NHTSA). We had NO warning lights, no overheating issues. Repairs have been made to the cost of almost $5400.00 *Please note there are many, many people complaining of this same issue on this model of car in multiple on-line forums.

NHTSA ID

11747660

Incident

May 4, 2026

Cylinder head suddenly cracked, causing heavy oil leakage onto hot exhaust manifold. Car started to smoke heavily. Vehicle turned off before potential engine fire.

NHTSA ID

11744932

Incident

Jun 6, 2026

I am submitting this complaint regarding a cylinder head failure on my Mazda CX-5. The vehicle has approximately 53,000 miles and has been properly maintained throughout its service life. The vehicle developed a crack in the cylinder head, which was subsequently confirmed by an authorized Mazda dealership. Mazda has previously issued a Technical Service Bulletin (TSB) addressing cylinder head cracking on certain vehicles; however, my vehicle's VIN is not included in the covered range despite experiencing the same failure described in the TSB. The dealership initially provided a repair estimate of $8,789 plus tax to replace the cylinder head. Following further discussions, the dealership reduced the repair cost to $3,903 plus tax. They recognize that this crack is not part of normal wear and tear but due to the VIN number not being included in the recall are unable to provide full coverage. A cylinder head crack is a major engine failure that should not occur on a well-maintained vehicle with only 53,000 miles. I am concerned that vehicles outside the VIN range identified in Mazda's TSB may be experiencing the same defect and that the scope of the issue may be broader than currently recognized. The vehicle was purchased used from the same Mazda dealership that diagnosed the failure and is currently performing the repair evaluation. I respectfully request that NHTSA review this issue to determine whether additional Mazda CX-5 vehicles may be affected by the same cylinder head defect despite not being included in the existing TSB.

NHTSA ID

11744861

Incident

Jun 12, 2026

2018 Mazda CX-5 AWD with 2.5 L engine, non turbo. Car has 98,914 miles. Rear differential started leaking oil. Dealer stated that the differential needs to be replaced, for $5,003.33. Manual does not provide for oil change intervals. Lifetime oil. 98K must be the life expectancy. Has not been fixed yet. Sitting in the garage dripping oil onto a piece of cardboard. independent shop looking for a low mileage used differential.

NHTSA ID

11742164

Incident

May 6, 2026

This SA supersedes the previously issued SA(s) listed below. The changes are noted in Red. SA-061/25 12/17/25 DESCRIPTION If you encounter any type of electrical concern (e.g, dead battery, engine no start, DTC(s) stored...), interview the customer before proceeding with normal MGSS diagnosis by asking if any aftermarket devices have been installed. Aftermarket devices may be the cause of the electrical concern. Below are a few examples of unusual electrical concerns caused by aftermarket devices. Examples: 1. Devices connected to the DLC-2 (battery discharge/DTC stored) 2. Devices plugged into the 12V outlet 3. GPS tracking device (engine no start/battery discharge) 4. Dash cam (DTC stored) 5. Non-certified USB cable (Apple Carplay™/ Android Auto™ will not connect) 6. Over-sized wheels/tires (incorrect GPS location) 7. DTC C0023:14 8. Decorative trim and/or cover on the START/STOP ENGINE button Example 1: Some electrical devices connected to the DLC-2 connector by insurance or mobile phone companies may cause: Battery discharge. The device may disrupt the CAN system battery saver mode. • IDS/MMDS will not communicate with the vehicle due to poor DLC-2 connection. The aftermarket device may cause DLC-2 female terminals to spread open.

This bulletin supersedes the previously issued bulletin(s) listed below. The changes are noted in Red. 01-008/23 06/05/23 Some vehicles may exhibit rattling noises from the engine compartment and oil leakage from the drive belt auto tensioner. This may be caused by insufficient sealing at the drive belt auto tensioner damper when the auto tensioner fully operates under both high ambient temperature and high load conditions. To eliminate this concern, the shape of the drive belt auto tensioner damper has been changed. REPAIR PROCEDURE If the tensioner is found to be "No Good" after completing the Drive Belt Auto Tensioner Inspection, replace it with a modified part according to the instructions on MGSS online:

DESCRIPTION Some vehicles may require the replacement of a damaged VIN plate or vehicle certification label. To obtain a replacement VIN plate (bulkhead-mounted and visible through the lower-left area of the windshield), contact DAG (Dealer Assistance Group) using VIN Plate Request Form available on One Mazda. To obtain a replacement vehicle certification label (located on the B􀀀pillar or front door), contact your assigned DSM (District Service Manager) to place the order. If DSM contact information is not available, refer to the Dealer & Field Contact Directory.

This Service Alert supersedes the previously issued SA listed below: The changes are noted in Red. SA-011/24 02/12/24, 06/06/24, 07/29/24 DESCRIPTION Mazda has developed factory recommended scheduled maintenance services that support all major vehicle systems. Mazda recommends dealers follow the scheduled maintenance tables as cited in the vehicle-specific workshop manual or owner's manual. Services performed outside of Mazda's factory scheduled maintenance are not recommended. These services are unnecessary and create unneeded expenses for your customers. SCHEDULED MAINTENANCE Refer to the applicable Workshop Manual or Owner's Manual for vehicle -specific manufacturer scheduled maintenance. Workshop Manual - Refer to section 00-00 SCHEDULED MAINTENANCE. Owner's Manual - Refer to section 8 Maintenance and Care. b. Note: Please refer to the information below outlining the services not included in Mazda's Factory Scheduled Maintenance: IMPORTANT: Recommending fluid flushes when not necessary can lead to customer confusion and dissatisfaction. Fluid flushing for preventive maintenance purposes is strongly discouraged, unless otherwise specified in a published procedure (Owner’s Manual, Workshop Manual, Technical Service Bulletin, etc.).

This Service Alert supersedes the previously issued M-Tip(s) listed below. The changes are noted in Red text. MT-002/19 09/30/19 and 12/19/19 DESCRIPTION If an engine assembly is replaced after a catastrophic internal mechanical failure, clean the intake manifold internally before installing a replacement engine assembly. If the intake manifold is not cleaned properly, the replacement engine may fail prematurely. Metallic debris from the old engine (with catastrophic internal mechanical failure) may rest inside the intake manifold. When the new engine assembly is installed, debris in the intake manifold will be ingested into the new engine and cause internal damage. Clean the intake manifold internally to remove any debris from old engine before installing the new replacement engine assembly. If the intake manifold cannot be properly cleaned internally, replace it.

This Service Alert supersedes the previously issued M-Tip(s) listed below. The changes are noted in Red text. MT-003/22 03/02/22 DESCRIPTION Some customers may complain about a tapping or knocking noise coming from the rear seat after fuel fill. The concern will likely occur if the fuel tank is overfilled (more fuel is added after the fuel pump nozzle shuts off automatically) or filled up normally in high ambient temperatures and the fuel expands. No repair is needed. Explain to the customer not to continue filling after nozzle shut off.