2018 Mazda CX-5: sudden loss of power

Filed Jul 1, 2026 · Transmission · CA

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 (the federal safety agency). 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.

Filed Mar 7, 2026 · Engine · KY

Vehicle developed burning oil smell. Dealership diagnosed a cracked cylinder head. No warning lights (yet. Eventually low oil pressure light would come on.) Potential for engine to lock up and lose power while driving putting occupants and others at risk. Know problem for 2018-2021 model years. Car no longer under warranty. Cost to repair $7,100. Technical Service Bulletin SA-031-21 issued regarding this problem.

Filed Jan 29, 2026 · Engine · PA

While driving, my 2018 Mazda CX-5 experienced a sudden and complete loss of engine power without warning. The engine shut down while the vehicle was in motion; however, electrical systems such as the radio, heat, and electronics remained operational. The vehicle lost propulsion, creating a serious safety risk in traffic. The vehicle had recently been serviced at an authorized Mazda dealer for completion of PCM and fuel-system recalls. Shortly after recall service, the engine failure occurred. No warning lights or prior symptoms were present. An independent mechanic suggested possible engine seizure, but a full diagnostic evaluation (including compression testing or internal inspection) has not been completed. The cause of the sudden power loss remains undetermined. This incident represents a potential safety defect involving unexpected engine shutdown and loss of propulsion.

Filed May 13, 2021 · Engine · 38,650 miles · CA

Situation: driving uphill on hwy 120 on new priest road, big oak flat, ca, two lane mountain road. Slow car in front of me and a delivery truck tailgating. Slow car eventually moves aside in a turnout and I accelerate to open up space between myself and what I thought would be the truck but somehow the slow car returned to the driving lane ahead of the truck. I continue to accelerate to attempt to open up space between myself and the car behind me when I lost power, the car behind me moves to the opposing traffic lane to avoid rear ending my car that is running in degraded mode (accelerator has no effect, basically moving on idle power) and narrowly misses an oncoming car as I move towards the right edge of the right lane. Truck behind me has to brake hard to avoid rear ending me. There was no shoulder to pull over to at that location immediate location. I pull over a few hundred yards further at a safe location. Grade was perhaps 4% to 6%. Weather: hot 90 degrees speed: accelerating from 35 to 50 MPH (guess) diagnostic lights: smart city braking system failure warning, plus a lot of other warning lights lit including check engine light. Aftermath: I pulled safely over, stopped the engine, waited a while and restarted the engine and the car returned to it's normal driving behavior and completed my trip. Other information: this is the 3rd occurrence of this behavior. Each time I have had mazda look at the problem. 1st occurrence they replaced the cylinder coil, 2nd occurrence they replaced a spark plug for misfire. 3rd occurrence, to be determined.

Filed Nov 12, 2019 · Engine · NJ · crash

Mazda cx-5. Consumer writes in regards to vehicle being totaled as a result of loss of engine power. *ld