2018 Cadillac XT5 Steering Problems

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.

NHTSA ID

11740245

Incident

May 15, 2026

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.

NHTSA ID

11737788

Incident

May 7, 2026

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

NHTSA ID

11712970

Incident

Jan 19, 2026

Cadillac XT5 had a “steering assist is reduced” message on the driver information center. P0128 Code

NHTSA ID

11692134

Incident

Jul 27, 2025

2018 xt5 code p128 steering assist is reduced drive with care its only has 37.282 miles on it steering got hard to control

NHTSA ID

11682768

Incident

Aug 1, 2025

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.

NHTSA ID

11674072

Incident

Jul 9, 2025

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.

NHTSA ID

11578386

Incident

Mar 3, 2024

Dash alert: Steering Assist is ResucedDrive with Care I see this is a current problem with the 2018 Cadillac XT5 but my VIN doesn’t seem to be included. Please investigate why mine would not be included if I suddenly have the same issue.

NHTSA ID

11559499

Incident

Dec 1, 2023

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

NHTSA ID

11535878

Incident

Sep 20, 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.

NHTSA ID

11510861

Incident

Jun 1, 2020

When I get on the freeway and go around 68 mph my vehicle starts shaking and I constantly get a stabilitrak message that flashes on and off. I have to hold the steering will tight because it swerves a little and had to start driving away from cars. I took it to get the wheels balanced and it still does the same thing. The mechanic from the dealer ship I purchased the vehicle from said he could not find anything wrong with it.

NHTSA ID

11441811

Incident

Nov 2, 2021

The contact owns a 2018 Cadillac XT5. The contact stated while the vehicle was stationary at a traffic light, the Stabilitrak warning light was illuminated for a short time and turned off when depressing on the accelerator pedal. The contact stated that on 11/19/2012, while his wife was driving 45 mph, the reduced steering capacity, pull over immediately and other multiple unknown warning lights were illuminated. The driver stated that the steering wheel became difficult to turn however, the driver was able to continue driving to her residence. The contact towed the vehicle to the local dealer, where it was diagnosed with needing the battery to be replaced. The vehicle was repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 32,000.

NHTSA ID

11441284

Incident

Nov 7, 2021

Mileage

32,000 mi