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Software Bug Stalls Prius Hybrid Cars
By Nate Mook, BetaNews
October 14, 2005, 12:45 PM

Toyota plans to notify buyers of its Prius hybrid that the car could
potentially stall out while driving due to a software bug in the
Electronic Control Module (ECM). The problem affects approximately
75,000 cars, although only 33 official complaints have been lodged
thus far.

Due to the bug, the Prius' gasoline engine could stall out while
driving between 35 and 65 miles per hour. However, the car's electric
engine would take over, enabling a driver to safely reach the side of
the road. Upon stopping, the gasoline engine would properly restart,
Toyota says.

Aside from the complaints made to the National Highway Traffic Safety
Administration, Toyota has connected about 416 incidents to the
software error and decided to contact customers about the defect. No
injuries or accidents have been attributed to the bug, the company

Customers will receive a notice later this month instructed them to
take their Prius to a dealer for the free software upgrade that
resolves the problem. Aside from the bug in the ECM, Toyota will also
fix a mechanical problem that can lead to stalling as well.

"This remedy should address most of the incidents," Toyota said on
its Web site.

The Prius has become a hot seller this past year as gasoline prices
continue to soar. September sales were up 90 percent from 2004, and
Toyota expects to sell upwards of 200,000 Prius hybrids next year
alone. With its gas and electric engine working in unison, the Prius
can average close to 50 miles per gallon and never needs a charge

7,161 Posts
Toyota really should make the firmware updates available whenever they happen, and not just a TSB that is covered only if a problem exists. If I am not mistaken, applying a new calibration to an ECM takes only 1/2 hour, and could be done while an oil change is performed.

Of course the engine could not be started to check for leaks until the programming is complete.
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