2018 Cadillac XT5

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.

Thermostat failure causes steering assist to be reduced. This leaves more difficult steering especially in an emergency situation, thus a safety concern. The vehicle displays a warning: "Steering Assist Is Reduced, Drive with care". An internet search shows this is a well-known problem across all General Motor vehicles. This is also indicated by the technician notes on my repair invoice that a bulletin from the manufacturer has been issued. After restart the warning clears leaving the driver to believe all is well. After a number of miles it reappears.

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 NHTSA 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

Message on dashboard "steering assistance reduced drive with caution". Messages appeared April 2025 and July 2025. Previously electric module needed to be replaced. Steering message caused me to be very cautious. Radiator had to be replaced because of leak. Both issues repaired at dealership. Vehicle has less than 40,000 miles.

A/C stopped working. Steering assist is reduced warning light came on. Was told it was a thermostat/ sensor. Had the sensor replaced for a cost of approximately $230.00. Short while later, A/C stopped working again. Suddenly the Steering wheel malfunctioned while driving on the interstate. Ran off the the road into median and heard a loud "Pop" sound as I tried to gain control of the vehicle. Hit an embankment and almost crossed over median into oncoming traffic. All airbags deployed. My passenger and I suffered injuries including broken bones, fractured ribs, severe back and shoulder pain, bleeding forearm, bruises and swelling. We were transported to a nearby ER by ambulance. The Vehicle was totaled.

FROM THE TIME I PURCHASED MY VEHICLE THEIR WAS A POPPING NOISE WHEN I TURN STEERING WHEEL I PURCHASED AT CARMAX AND TOOK IT BACK TWO OR THREE TIMES THEY SAID NOTHING WAS WRONG..I TOOK.IT TO SEWELL CADILLAC THEY SAID NOTHING WAS WRONG..IF I'M NOT MISTAKEN I TOOK TO STERLING CADILLAC THEY SAID NOTHING WAS WRONG.MY LAST OIL CHANGE WAS AT STERLING CADILLAC IN BRYAN TX A FEW WEEKS TO A MONTH AGO NOW THEY TELL ME IM IM DANGER AND THEY NOW HEAR THE NOISE AND SAYS ITS MY STEERING COLUMN AND NEEDS TO BE REPAIRED IMMEDIATELY..THEY ARE NOW CONCERNED SINCE MY CAR NO LONGER HAS A WARRANTY..I TOOK MY CAR BACK.TO.CARMAX 2 TO 3 WEEKS AFTER PURCHASE AND KEPT TELLING THEM ABOUT THE NOISE THEY SAID WAS NOTHING AND NOW I'M TOLD WHAT I KNEW IN 2019

The contact owns a 2018 Cadillac XT5. The contact stated that while driving at various speeds, the steering power reduced warning message was displayed. The manufacturer was notified of the failure and referred her to the local dealer for assistance. The contact was also informed that there were no recalls on the vehicle. The vehicle was not repaired. The contact had not experienced a power steering failure in spite of the frequent illumination of the message being displayed. The failure mileage was unknown.