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Honda Pilot Stop-Start Failures Under Investigation By NHTSA

The federal regulator is investigating reports regarding engines not restarting after the auto stop-start system activates.

The NHTSA has opened an investigation into certain Honda Pilot models regarding engine issues, reports Automotive News. The issue concerns the operation of the auto start-stop system, in which the vehicle’s engine fails to restart after a stop.

The Office of Defects Investigation at the NHTSA reports 221 complaints covering vehicles from the 2016 to 2019 model years. The regulator has opened a probe into the issue, covering 194,731 vehicles in the US, including 2020 model year vehicles. The investigation concerns models fitted with the 3.5-liter V6 engine paired with the 9-speed automatic transmission.

Auto start-stop systems are configured to shut down the engine when pulling up to a stop, such as at a traffic light or stop sign. When the driver wishes to proceed again, the engine is quickly restarted. Shutting the engine down in this manner saves gasoline that would otherwise be used to keep the engine idling, and reduces emissions in turn.

NHTSA documents state that in affected vehicles, the “engine fails to restart on its own from a complete stop at a traffic light or road intersection.” In some cases, a jump start is apparently required to restart the vehicle.

The latter piece of information is particularly interesting. If the vehicle needs a jump start to restart the engine after the stop-start system kicks in, it would be indicative of a battery that is borderline too weak to turn the engine over. It may be that some examples are down to batteries in poor condition, while other cases have a different cause.

Alternatively, it may be that Honda’s stop-start system is engaging too soon after the vehicle has been started. Particularly in cold conditions, an older battery can take a little while to charge back up to the point where it can restart the engine. If the stop-start system is engaged too soon, a weak battery won’t have enough juice to get the engine going again unless it’s charged more or given some time to recover.

In talks between Honda and the NHTSA, the automaker revealed that other models have also experienced the same issue. Models of the Honda Odyssey and Acura TLX and MDX have all been subject to this issue, with the problem shared amongst vehicles fitted with the same J35Y6 V6 engine and the ZF 9HP 9-speed transmission.

Spokesperson Chris Martin told Automotive News that Honda was aware of the issue and is committed to safety in its vehicles. “Honda will cooperate with the NHTSA through the investigation process, and we will continue our own internal review of the available information,” said Martin.

The NHTSA investigation will proceed to determine the nature of the problem and the severity of its impact. The federal regulator may then issue a recall request to Honda at its discretion, asking the automaker to rectify the problem. Of course, Honda may institute a recall repair of its own volition, a move that seems likely given the company’s open admission of the problem.

If you’ve been having stop-start issues with your Honda and it’s rocking the same drivetrain, you’ll want to keep an eye on developments. Feel free to let us know about your experiences of the problem in the comments below.

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