Federal regulators are warning that certain older Ford cars and SUVs equipped with a specific engine pose an "unreasonable" safety risk, citing potential timing belt failures that can cause sudden power loss or engine seizure while driving.

The National Highway Traffic Safety Administration (NHTSA) announced on Monday that it has escalated a defect investigation covering 135,551 Ford vehicles from the 2014–2021 model years. All affected vehicles are powered by Ford's 1.0L turbocharged three-cylinder engine, marketed as the EcoBoost. The three models in question — the Fiesta, Focus, and EcoSport — have all been discontinued by the automaker as Ford shifted its product lineup away from small passenger cars toward trucks and larger SUVs.

According to the agency, it has identified 355 incidents in which a low engine oil pressure warning light illuminated shortly before drivers experienced a complete or partial loss of motive power.

NHTSA's preliminary investigation determined that the timing belt material may degrade over time, shedding debris that clogs the mesh oil pump pick-up screen. This blockage reduces engine oil pressure and can lead to catastrophic failure. Timing belts, unlike timing chains, are designed as wear items requiring periodic replacement. The agency noted that such failures may occur without adequate warning, and that affected drivers could face imminent engine seizure or power loss. Importantly, these failures have been reported even in vehicles that received proper and routine oil maintenance.

"Based on NHTSA's analysis of the data, failure rates, information provided by Ford, preliminary engine teardown analysis, and precedent recalls regarding loss of engine oil pressure with the presence of driver facing warnings, (the agency) believes there is an unreasonable risk to motor vehicle safety," the NHTSA stated.

The upgrade of the probe to an engineering analysis — the second and more advanced phase of NHTSA's defect investigation process — represents a necessary procedural step before the agency could compel Ford to issue a formal safety recall.

Some affected drivers have reported repair costs reaching thousands of dollars. One owner of a 2017 Ford Focus described being on a highway in Wilmington, Delaware, when the oil pressure warning light illuminated. Within an eighth of a mile, the vehicle "lost all power and the engine began to sound like a tank," according to the driver's report.

NHTSA data indicates that the average mileage at failure was approximately 70,000 miles, with 98% of incidents occurring before the manufacturer's suggested timing belt replacement interval of 150,000 miles.

In June, Ford informed the safety regulator that it was implementing a non-safety customer satisfaction program for global vehicles equipped with the 1.0L Fox Classic Timing Belt. Unlike a federally mandated safety recall, a customer satisfaction program is a voluntary manufacturer initiative. Under this program, the recommended maintenance interval has been reduced to 100,000 miles or six years.

NHTSA also noted that Ford is offering reimbursement to eligible customers who previously paid for engine repairs or replacements related to timing belt issues. However, the specific vehicles covered under the customer satisfaction program were not immediately clear.

The original report is available at Fox Business. Reuters contributed to this report.