Start-stop systems have improved over the years. Instead of a disconcerting shudder whenever the engine shuts off and restarts, modern vehicles offer much smoother transitions. But what if the engine fails to restart at all? American Honda Motor Company is currently under investigation following reports of such a failure that could affect more than two million vehicles between its Acura and Honda brands.
According to a new investigation by the National Highway Traffic Safety Administration, more than 1,348 complaints regarding the automaker’s automatic start-stop system have been filed. Among the reports are incidents that resulted in a crash or fire as well as injuries.
The complainants allege that when the Auto Idle Stop system is activated, the engine will fail to restart following a complete stop. In some instances, a jump start was needed to get the vehicle going again.
NHTSA says a preliminary evaluation began in June 2022 regarding 2016-2019 model year Honda Pilot vehicles. The restart failure seemed to only affect Pilots equipped with the 3.5-liter V6 engine and 9-speed automatic transmission pairing.
However, a series of service bulletins beginning in January 2023 included additional Honda models—the 2019-2022 Passport and 2020-2023 Ridgeline—as well as the 2015-2020 TLX and 2016-2020 MDX from its Acura lineup. In total, this includes an estimated 2,209,466 vehicles.
The Honda service bulletins outlined a two-stage repair. The first part was a software update while the second countermeasure, which was determined by model and year, involved replacing the starter assembly, starter relays, and a valve adjustment. Vehicles that needed components replaced were given an extended warranty of 10 years.
But the fixes didn’t work, and vehicles are still not restarting. More than an annoyance, this puts the drivers and occupants at risk of collision or injury.
If enabled, start-stop features will do as their name indicates. Intended as a fuel saver, the system will shut off the engine when a vehicle comes to a complete stop. By minimizing the idling time, less fuel is used and fewer emissions are emitted. But sometimes, the engagement isn’t as fast as people would hope, the fuel savings are not that great, and your car shutting down is still a feeling to get used to.
Also, because the system can kick whenever a vehicle comes to a stop, the risk of a crash increases when stoppage leads to a stalled car. If crawling through traffic, an inop vehicle becomes all manner of inconvenience and frustration. If on a highway, the dangers rise due to the higher speed of traffic.
Being stranded at an intersection isn’t any better. You’d hope to be more visible, but not every junction is going to be a flat, straight four-way stop. Stuck in a roundabout where some drivers don’t even slow down would be unnerving. The above risks only increase at night.
The timeline for when a new fix is offered is unknown. While another remedy is being looked into for the recurring start-stop problem, the good news is that the system can be manually deactivated.