2018 Mazda CX-5

Cracked cylinder head- factory defect, causing oil to leak onto exhaust manifold. Smoke fills engine bay and cab through air vents, very high concern of engine bay fire. 2018 Mazda cx5 non turbo 2.5 sky active engine. Mazda knows of this defect and will not proved remedy.

There has been numerous report of the Mazda CX 5 having failure rear differential. I just purchased a 2018 Mazda CX five for my daughter in September 2026 I now am experiencing this issue on the rear diff. The dealer will not cover the repair since it’s as is purchase Mazda should take this as a recall and fix the vehicle for the safety of the consumer.

2018 Mazda CX-5 2.5L NA Engine Cracked cylinder head and blown head gasket with leaking oil onto exhaust manifold resulting in white smoke & burning oil smell. No engine light. Issue confirmed by dealer and independent shop. Commonly reported issue amongst 2018-2021 Mazda CX-5 owners either naturally aspirated engines.

The contact owns a 2018 Mazda CX-5. The contact stated that while driving at various speeds, the vehicle was leaking engine oil, and there was white smoke coming from underneath the hood. The contact stated that upon further inspection, there was a puddle of engine oil on the ground while the vehicle was idling. No warning light was illuminated. The vehicle was towed to a local dealer, where it was diagnosed with a cracked cylinder head. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 183,540.

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.

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)

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

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.

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.

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

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.

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.