Honda Transmission Problems: Lawsuit Says Pilot, Odyssey, Passport, Ridgeline Plagued by Programming Defect

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A proposed class action alleges the nine-speed automatic transmission found in certain model year Honda Pilot, Odyssey, Passport and Ridgeline vehicles suffers from a programming defect that can cause rough or delayed shifting, among other serious safety concerns. 

Do you own or lease a 2018-2019 Honda Odyssey, 2019-2023 Honda Passport, 2020-2023 Honda Ridgeline or 2016-2022 Honda Pilot? Let us know here. 

The 55-page complaint says that the apparent defect plaguing the ZF 9HP transmission in 2016-2022 Honda Pilot, 2018-2019 Honda Odyssey, 2019-present Honda Passport and 2020-present Honda Ridgeline vehicles can produce rough and delayed shifting; loud noises during shifting; sudden, harsh accelerations and decelerations; and a sudden loss of power. 

According to the lawsuit, the Honda transmission problems are the result of “design and/or workmanship defects” stemming from the “improper design and/or calibration” of the ZF 9HP transmission’s control software, including affected vehicles’ transmission control module and powertrain control module. The filing stresses that it is the responsibility of Honda to ensure that the transmission control software, which is produced by a component manufacturer, is properly calibrated for use in its vehicles, particularly with respect to how the transmission control module communicates with other modules and responds to sensor data. 

The suit explains that the calibration defect can cause both the transmission control module and powertrain control module in affected Honda vehicles to become “unduly sensitive” to variations in signals from the sensors that communicate with them. 

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“Overall, due to the Transmission Programming Defect, the [transmission control module] does not communicate properly with the [powertrain control module] and respond correctly to incoming sensor data, and as a result, gear shifting, among other functions, is mistimed,” the lawsuit summarizes. 

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Although a traditional automatic transmission will shift between six gears to provide the most appropriate gear ratio for a given situation, the ZF 9HP transmission in the Honda models at issue differs in that it employs a 9.8 ratio spread, which, ideally, allows for shorter shifts between gears, the case states. This keeps the engine in a “narrow, optimal band of RPMs [revolutions per minute] for as long as possible” and contributes to greater fuel efficiency, the suit relays. 

Moreover, the ZF 9HP transmission “borrows” characteristics typical of manual transmissions, such as “dog clutches,” which the suit says “use less power to shift than the friction clutches” used in automatic transmissions. Importantly, the ZF 9HP transmission engages the dog clutches using software commands from an electronic control unit, supposedly to “save space and ensure that the complex transmission actually fits inside the vehicles,” the lawsuit states. 

The filing shares that one automotive journalist explained that the ZF 9HP’s use of software, unlike other automatic transmissions, causes “a somewhat odd delay between the pedal on the floor and the car taking off like a bat out of hell.” In light of this, the lawsuit contests that the transmission problems hampering the Honda Pilot, Odyssey, Passport and Ridgeline cause the vehicles to operate “erratically” and can hinder a driver’s overall ability to control the car. 

“For example, these conditions may make it difficult to change lanes safely, make turns, merge into traffic, and accelerate from stop [sic] at intersections, because Class Members’ vehicles can fail to respond correctly to driver’s input during these normal traffic conditions.” 

The suit says that Honda, despite issuing to dealers nationwide numerous technical service bulletins “acknowledging” the transmission problem and its symptoms, has failed to find a fix for the issue, and consumers allegedly continue to deal with rough, delayed or sudden shifting; grinding or other loud noises during shifting; harsh gear engagement; sudden loss of power; and sudden/harsh accelerations or decelerations. 

Further, Honda has not issued a warranty extension for the vehicles at issue, recalled the cars or offered drivers suitable repairs or replacements free of charge, the case notes. 

“In fact, instead of repairing the defects in the ZF 9HP Automatic Transmission, [Honda] performed work on the Class Vehicles, such as software updates, that simply masked the defects,” the complaint alleges. 

The lawsuit looks to cover all consumers in the United States who bought or leased any Honda vehicle equipped with a nine-speed automatic transmission. 

Do you own or lease a 2018-2019 Honda Odyssey, 2019-2023 Honda Passport, 2020-2023 Honda Ridgeline or 2016-2022 Honda Pilot? Let us know here.