Cadillac CT6 Gets Extended Transmission Control Valve Warranty Coverage

The 2019 Cadillac CT6 and 2020 Cadillac CT6 have been included in a bulletin from GM granting extended special coverage for a transmission valve defect that can cause wheel lock-up and possible accidents or crashes, which also led to a recall.

Coverage for the defect and its eventual fix has been extended to 15 years or 150,000 miles, whichever comes first, according to GM Special Coverage Bulletin number N242480631.

The bulletin also describes the fix to be made available for the affected Cadillac CT6 units. Currently, remedy parts are only available for CT6 sedans motivated by the turbocharged 2.0L LSY I4 gasoline engine. Those equipped with the naturally aspirated 3.6L LGX V6 gasoline engine or the twin-turbocharged 4.2L TT LTA V8 gasoline engine are also involved, but have no fix currently available.

GM service personnel are instructed to carry out the repair by replacing the control valve body assembly. This includes several seals and 9 quarts of Dexron ULV transmission fluid to refill the transmission after the fix is applied. Notably, the problem only affects Cadillac CT6 units equipped with the GM Hydra-Matic 10-speed automatic transmission.

As a reminder, Safety Recall number N242480630 is the recall involved. The issue is a defective transmission control valve that is made out of incorrect material that wears out much faster than it should. This causes the valve to lose pressure, initially leading to harsh shifting. As the valve wears more, it can cause the wheels to momentarily lock up when the transmission downshifts from 8^th to 7^th gear, potentially leading to a high-speed accident or crash.

Until now, the remedy was installation of new software that enables the Transmission Control Module to detect the issue approximately 10,000 miles before lock-up would occur, and limits the Cadillac CT6 to 5^th gear at maximum, reducing propulsion. The current fix is a follow-up to this temporary solution that will be extended to all vehicles as parts become available.

The now discontinued North American variant of the Cadillac CT6 rides on the GM Omega platform and was produced at the GM Detroit-Hamtramck plant, now the site of the GM Factory ZERO plant.