While driving at approximately 49 mph in a 40 mph zone on dry pavement in daylight with AWD mode active, the Driver Information Center displayed the warning "Steering Assist is Reduced, Drive with Care." Steering effort increased noticeably; steering was not completely lost. No check engine light appeared with this event. No crash, fire, injuries, or police report resulted. This failure is reported by other 2021 XT5 owners as intermittent and can recur without warning, degrading the driver's ability to make an evasive maneuver, especially at low speeds where pedestrian and parking-lot conflicts occur. Suspected root cause per owner reports and GM service documentation: engine coolant thermostat failure triggers a false engine temperature signal, and the electric power steering system reduces assist as a thermal protection response. Companion symptoms reported: inoperative/incorrect temperature gauge, cooling fans running at high speed continuously, A/C performance loss, DTC P0128. Manufacturer documents: Cadillac Service Bulletin 20NA215 (corrects "Steering Assist is Reduced Drive with Care" on 2021 XT5); GM Service Bulletin 17-NA-284 (2017-2018 XT5/GMC Acadia, reduced steering assist message with DTC C0460 Sym 5A, steering angle sensor trim error); GM Special Coverage N252508350 for the engine coolant thermostat (15 years/150,635 miles, expiring March 1, 2036). The vehicle carries a rebuilt title, so GM's warranty block applies and the owner may be denied the special-coverage remedy that a safety recall would guarantee to all owners regardless of title status.
Cadillac XT5 check engine light comes on
31 of the 314 owner complaints about the Cadillac XT5 describe check engine light, most of them for the 2017 model year.
- owner complaints
- 31
- worst model year
- 2017
- typical mileage
- 2,500
By model year
Often reported together
Power steering loss 4Warning lights 3Stalling 2ABS 2Won't start 1Wipers 1Transmission failure 1Steering lock-up 1
Trouble codes mentioned
P0128 6P26C8 1C0460 1
What owners say
My 2019 Cadillac XT5 has repeatedly shuddered at highway speeds since shortly after purchase on July 25, 2026. It occurs around 61–62 mph while maintaining speed before accelerating. The cause is UNKNOWN. The selling dealership evaluated the vehicle and performed a front-wheel alignment, but the shuddering persists. Its repair record states that technicians could not reproduce the shuddering during a test drive. A test drive with me was proposed to demonstrate when it occurs. The vehicle has also displayed a “Steering Assist Is Reduced—Drive With Care” warning and a check-engine light. The steering felt normal despite the warning; I am not claiming an actual loss of steering. The temperature gauge has remained on cold, and the air conditioning has malfunctioned. The exact date the steering warning first appeared is UNKNOWN. On October 21, 2026, another Chevrolet dealership documented diagnostic code P0128 and recommended thermostat/coolant-temperature-related repairs. Those repairs have not been performed. The manufacturer was contacted and declined repair assistance. Dealerships have inspected the vehicle; I am not aware of a separate inspection by the manufacturer. I am concerned about the persistent shuddering at highway speeds and the warning of potentially reduced steering assistance. The cause of the shuddering and its relationship, if any, to the other symptoms remain unconfirmed. I still have the vehicle. Repair records, diagnostic information, and photographs of warning messages are available.
The contact owns a 2020 Cadillac XT5. The contact stated that while driving at an undisclosed speed, the transmission unexpectedly shifted into different gears. The Check Engine warning light was illuminated. The failure persisted while the contact's wife was driving, and the vehicle lost motive power. The vehicle was able to restart and shift into gear. The contact notified Carvana of the failure and was referred to several independent mechanics, who informed the contact that they did not service vehicles purchased from Carvana. The vehicle was taken to the dealer, who determined that the brakes and rotors, front control arms, radiator, unknown sensors, and several other unknown parts needed to be replaced; however, the contact stated that the recommended repairs were not related to the failure. The vehicle was towed to the residence. Carvana was contacted again and referred the contact to the second dealer, Herb Chambers Cadillac of Warwick (1511 Bald Hill Rd, RI-2, Warwick, RI 02886), who determined that the computer was not communicating with the key fob, and the coolant sensor, the air conditioner, and several other unknown parts needed to be replaced; however, the dealer informed the contact that they were unable to file a claim with Carvana to repair the vehicle. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 68,000.
Check engine light sensor came on in mid-May which is the result of a faulty thermostat, also triggering a "Steering Assist is Reduced" message on the dashboard which I consider to be a safety issue. This is a known and common problem for this make, year and model and the cost to fix the problem is very expensive. This issue has been reported by many Cadillac owners on their forum. My mechanic confirmed the problem with the thermostat caused the steering assist is reduced message, along with the air conditioning malfunctioning.
I purchased this used car in the end of July 2025. Within the last month the service transmission light came on. Within a 24-hour period, the message changed to, "service transmission unable to shift Soon". Also alarm bells go off when I first start the car and sometimes during driving. The car feels like it drives correctly and smoothly with no shifting issues. Sometimes when that second message and check engine light icon being comes on, there seems to be a third message that is trying to pop up behind it but it does not. It seems like there is a glitch in the system. This was very concerning and scary for me. My research shows me that this has been a chronic problem for my make and model and year of car. I've also heard it can be even time to check and or change the transmission fluid. That needs to be a different message all together without causing alarm that the transmission itself is not functioning properly. I have not driven this for 10 days because many repair shops in dealerships are telling me not to risk it and of course want me to bring this in for a diagnosis. It is costly and hard to discern and trust who to go to for the correct information. The dealership should be responsible for a recall and replacing this sensor or modular so people do not have a cause for alarm if it is something as simple as needing to change the transmission fluid. There is also no dipstick on this vehicle so no local fluid fill station can check this. Many people have complained and are at a loss. I see there is a bulletin on this subject but no recall. Please take action and turn this situation into a recall once and for all to help. The little folks like me stay more safe and better informed about the health and longevity of our vehicles. Thank you for your time in reading this.
To Whom It May Concern,I am writing to formally report a safety concern involving my 2018 Cadillac XT5, VIN [XXX] . Recently, my vehicle displayed a “Steering Assist Reduced” message on the dashboard while driving. This warning significantly increases the physical effort required to steer the vehicle, especially at low speeds, and I believe it presents a genuine safety hazard.Upon taking the vehicle to an authorized Cadillac dealership, I was informed that the vehicle had stored diagnostic trouble code P0128 (Engine Coolant Temperature Below Thermostat Regulating Temperature). The dealer explained that a malfunctioning thermostat caused the steering assist reduction message to appear. However, at no point did the vehicle illuminate a Check Engine Light, despite the presence of an emissions‑related fault code.I am concerned for several reasons:A critical engine fault (P0128) did not trigger a Check Engine Light, leaving me unaware of any underlying issue. The vehicle reduced power steering assist as a result of an unrelated thermostat malfunction, creating a sudden and unexpected increase in steering effort. This behavior poses a safety risk, particularly in situations requiring quick steering response or low‑speed maneuvering.Cadillac has issued Service Bulletin 17NA158, which acknowledges that thermostat or coolant‑temperature‑related issues can trigger steering assist warnings. This suggests the manufacturer is aware of the problem, yet no recall or corrective action has been issued.Given that steering assist reduction directly affects vehicle control, I believe this issue warrants investigation. A driver should not lose steering assist because of a thermostat fault, nor should a vehicle fail to illuminate a Check Engine Light when a diagnostic code is present.I respectfully request that the federal safety agency review this matter to determine whether a safety‑related defect exists in the 2018 Cadillac XT5 and similar GM vehicles. Sumitting this for my mother. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOI
The contact owns a 2019 Cadillac XT5. The contact stated that while leaving the driveway, there was an abnormal sound coming from the vehicle. The contact stated that while driving at 65 MPH, there was an abnormally loud squeaking sound coming from the vehicle. The check engine warning light was illuminated. The contact thought that the catalytic converter had been stolen. The vehicle was taken to an independent mechanic who determined that the catalytic converter was severed at the connection point and cracked, and removed. The contact stated that coils were damaged, and the thermostat housing was cracked. The vehicle was repaired, but the failure recurred. The local dealer was contacted, who determined that the catalytic converter had been replaced, but the failure persisted. The dealer informed the contact that the parts were on backorder. The manufacturer was not contacted. The failure mileage was approximately 100,000. The VIN was not available.
Check engine code p0128. driver assistance, air conditioning and steering affect.
The contact owns a 2018 Cadillac XT5. The contact stated that while driving at an undisclosed speed, the vehicle stalled with the check engine warning light illuminated. The vehicle was towed to the dealer where it was diagnosed that the engine had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 86,000.
Steering assist disengaged, low power mode, no temperature read and check engine light. All occurred at 61k miles.
Related recalls
No recalls on record for this model year.
Questions about the Cadillac XT5 check engine light
Why does the check engine light come on in the Cadillac XT5?
Owners who report it most often also describe loss of power steering, multiple warning lights and engine stalls while driving, and the codes they mention most are P0128, P26C8 and C0460.
Which Cadillac XT5 years have check engine light problems?
The model years with the most reports are 2017 (12 complaints), 2018 (7 complaints) and 2019 (7 complaints).
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