This preliminary informational (PI) bulletin provides information to dealership personnel that may be helpful when addressing underbody component corrosion with customers.
full bulletin at NHTSA ↗2017 Cadillac CT6 powertrain problems
moderate 16 complaints filed with NHTSA · avg repair $2,500 · see powertrain across all vehicles →
Failure mileage
Complaints
16
Recalls
0
Avg fix
$2,500
When does it fail?
Of the 16 powertrain complaints filed for the 2017 Cadillac CT6, here's the actual mileage breakdown — failures cluster heaviest at 0-25,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Of the 5 model years of Cadillac CT6 we track for powertrain problems, this one carries the most owner complaints on file — 16.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This Preliminary information communicates Diagnostic aids for a no start or DTC'S following a transmission replacement
full bulletin at NHTSA ↗This Preliminary information communicates Diagnostic aids for a no start or DTC'S following a transmission replacement
full bulletin at NHTSA ↗This service bulletin provides information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts, Slips, or Flares.
full bulletin at NHTSA ↗This bulletin provides information on identifying Non-GM Engine Calibrations for Gasoline Engines using the Tech 2 or GDS 2.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2017 CT6's 8-speed transmission is generating widespread complaints. The most common failure is harsh, violent shifting from 1st to 2nd gear—owners describe it as feeling like the car has been rear-ended. This occurs under light to medium throttle, often when accelerating from a stop or during startup. The auto stop/start system compounds the problem: when the engine restarts at a traffic light and the transmission re-engages, it lurches with such force that owners worry about collision or unintended acceleration into intersections. A few owners have also experienced shuddering, hesitation, and slipping during normal driving; one reports loss of all propulsion on the highway multiple times. Dealers have attempted transmission fluid exchanges, module reprogramming, and torque converter replacement without resolving these issues. GM issued Technical Service Bulletin 16-NA-361 in July 2017 acknowledging harsh 1-2 shifts upon first startup but stated there was no remedy. Multiple owners report that dealers now tell them this is a "known condition" and "normal," despite the vehicle lurching violently and the complaints being serious enough that one owner questions whether the car is safe to operate.
Same Cadillac CT6 powertrain reports on nearby years: 2019
Failure modes owners describe
Harsh 1-2 Upshift and Hard Shifting
Transmission produces violent or abrupt shifts between 1st and 2nd gear during acceleration. Owners describe the vehicle lurching or jerking forward suddenly, sometimes with enough force that it feels like the car has been rear-ended. Occurs under light to medium throttle and occasionally at full throttle.
When: Variable; often at startup or during initial acceleration from a stop; reported from under 1,700 miles to 14,000+ miles
Symptoms owners cite: Hard/harsh shift from 1st to 2nd gear; Violent lunge or jerk forward; Hesitation followed by sudden acceleration; Clunk or shudder during shift; Feels like vehicle has been rear-ended
Repairs/costs cited: One dealer mentioned defective torque converter and quoted expensive transmission replacement cost. TSB 18-NA-335 mentioned by one owner but issue persisted after service. Dealers have performed transmission fluid exchanges (one quoted $800) and transmission module reprogramming without resolving the issue.
Recalls/TSBs owners mention: TSB 16-NA-361 (Document ID 4605342) issued July 21, 2017 for 'Transmission Harsh 1-2 Shift Upon First Startup/Shift of the Day Under Light Throttle'—but noted 'no remedy for the failure.' TSB 18-NA-335 also cited. Multiple owners report dealer stating this is a 'known problem' and 'normal condition.'
Auto Stop/Start Malfunction with Harsh Re-engagement
When the auto stop/start feature shuts off the engine at stops and restarts, the transmission re-engages with a violent jerk or lunge. Owners report this occurs intermittently and can feel severe enough to be mistaken for a collision.
When: Occurs intermittently when vehicle is stopped and engine restarts; reported across multiple model years of ownership
Symptoms owners cite: Engine stalls/stops at traffic light or stop sign (auto stop feature); Harsh jerk when accelerating from restart; Violent lunge or surge forward upon re-engagement; Feels like vehicle has been hit from rear; May cause creeping into intersection
Repairs/costs cited: One dealer confirmed the problem was duplicated but no repair outcome reported. One owner noted the auto stop issue resolved after initial complaint but lurching on startup persisted.
Transmission Shudder, Hesitation, and Slipping
Transmission exhibits shuddering, vibration, hesitation, or slipping sensation during normal driving, acceleration, and deceleration. Owners report the vehicle feels like it is losing power or the transmission is not fully engaging. May be accompanied by whining noise from transmission or differential.
When: During acceleration and deceleration; at specific speeds (35, 45, 55 mph noted); reported from 1,700 to 24,000+ miles
Symptoms owners cite: Transmission shudder or vibration; Hesitation upon accelerator depression; Transmission slipping or dragging sensation; Lag in acceleration with humming noise; Whining noise from transmission or differential; Loss of power or engagement; Erratic gear changes
Repairs/costs cited: Dealers have attempted transmission fluid exchange, transmission module reprogramming, and torque converter diagnosis. One owner advised by dealer to bring vehicle back repeatedly for fluid changes.
Loss of Propulsion/Transmission Failure
Vehicle loses substantial or complete propulsion, particularly during highway driving. Owners report the vehicle substantially slows or stops without warning, creating a hazardous situation. Described as related to 'GAS/HYBRID ELECTRIC TRANSMISSION SYSTEM' design defects.
When: Reported as occurring on more than three occasions; first occurrence under 10,000 miles; one vehicle spent 62 of 92 days in shop awaiting repairs
Symptoms owners cite: Loss of propulsion or substantial loss of power; Vehicle slows or stops on highway; No acceleration response; Unsafe driving conditions
Repairs/costs cited: Vehicle remained in shop for extended period without repairs being completed.
Recalls/TSBs owners mention: Manufacturer acknowledged this as a 'known issue' with 'no viable permanent remedy' per owner complaint.
2-1 Downshift Harshness and Lurching During Braking
Transmission produces harsh downshift from 2nd to 1st gear during braking or deceleration, causing the vehicle to lunge forward. Owners report this is particularly dangerous when coming to a stop at intersections, as the vehicle lurches forward unexpectedly.
When: During deceleration and braking; reported as occurring regularly since acquisition
Symptoms owners cite: Hard/harsh downshift from 2nd to 1st; Vehicle lunges or pulses forward during braking; Nearly causes collision with vehicle ahead; Can cause vehicle to creep into intersection
Repairs/costs cited: Dealer reviewed and advised shifts are operating normally.
Transmission Gear Slippage in Coast and Turn Conditions
Transmission slips out of gear or shows slipping behavior during coasting, turns, or intersection navigation.
When: During normal driving in coast conditions and turns
Symptoms owners cite: Transmission slips or disengages from gear; Slipping occurs during turns and at intersections; Loss of drivetrain control
Synthesized from 16 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 12 most recent
These vehicles have an issue tbat GM is aware of, with their 8 speed automatic transmissions which are used in multiple GM vehicles and these cause safety issues because for instance my vehicle switches gears randomly almost causing a wreck, and shuttering, and even slipping and when this happens the cars traction control light is engaged shutting it off, active steering is also shut off due to…
Tl* the contact owns a 2017 Cadillac ct6. When the vehicle was started, it lurched forward without warning. The failure occurred intermittently. The vehicle was taken to gold coast Cadillac (732-709-2168, located at 2123 state route 35, oakhurst, nj 07755), but the cause of the failure could not be determined. The manufacturer was made aware of the failure and referred the contact back to the…
I was driving the vehicle heading to the interstate, and my speed was about 15 MPH, as I merge onto the highway and accelerated I felt the transmission shudder, and lag with a humming noise. It felt like the transmission mission was slipping and shaking with no acceleration power. I had to keep hitting the gas pedal to try and make the transmission engage. Very Dangerous! The transmission would…
While driving the vehicle with auto stop engaged, the auto stop was malfunctioning. When I get to a red light or stop sign vehicle would engage auto stop, once I let my feet off the gas pedal and accelerate, the vehicle would jerk out of gear then slip /drag then engage with a loud hit as if someone rear-ended me. The problem was duplicated and confirmed by the dealership. There has been no…
Vehicle's transmission lurches and slips out of gear in coast conditions; during turns and in intersections.
I purchased the used 2017 Cadillac ct6 in march 2019 with 24,192 miles. It was a certified pre -owned car by the dealer. Additionally I purchased a cpo protection plus protection plan with the car. I am experiencing problems with the transmission. During acceleration and decelerating the car feels a hesitation followed by a significant shake, shudder, jerk, clunk or hard shift. The auto…
Hard shifts in low speeds, intense vibration , shudder throughout driving speed. Cadillac dealer said it is torgue converter issue, car transmission needs to be fluid exchanged for $800.
The car is equipped with an 8-Speed Automatic Transmission which is frequently very hard shifting from 1st to 2nd gear. The car has been to my local Cadillac Dealer twice for this problem; they reply this is a know problem, and a normal condition, but the problem is getting worse. I'm concerned for the future and afraid of an accident because of a transmission failure.
Transmission has a signification clunk/hesitation/delay shifting up from 1st-2nd gear and down from 2nd-1st gear. In the upshift, the car violently lunges forward once the acceleration rev from the push of the pedal catches up with the gear shifting, no matter how delicately you might push the pedal. Feels like the vehicle has been hit from behind once it catches. In the downshift, upon…
Transmission - Jerks and studders (hesitation) in the course of normal driving. Brakes - Makes a squealing noise which has gotten louder over time.
Had powertrain trouble with your 2017 Cadillac CT6?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the powertrain problem on the 2017 Cadillac CT6?
It's a documented issue but not catastrophic. 16 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain typically fail?
Across the 9 complaints that reported odometer mileage, most powertrain failures cluster between 6,000 and 24,192 miles, with the median around 9,759. A quarter of owners report trouble before 6,000; a quarter make it past 24,192. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $2,500 for powertrain repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to powertrain?
No active recalls currently cover powertrain issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2017/Cadillac/CT6.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.