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.

My windshield has a lot of spider and has never been hit with anything. They spread from the bottom up

While driving at highway speeds, I needed to accelerate hard in order to pass another vehicle and while accelerating there was a downshift and increase in RPM. After passing, the RPM remained high even after I took foot off accelerator and it seemed the transmission did not shift back out of lower gear, keeping the car traveling at a high rate of speed, endangering myself and other traffic. Applying the brakes would not cause the engine to slow down and the engine kept working hard and traveling fast, causing strain on the brakes to slow down. I pulled over and initially shifted to neutral, but the engine was still revving high (4000 rpm observed). Then I placed the car in park which did not change the high RPM. Then I shut off engine and let it rest. Then I turned auto back on and all was normal. The problem has not yet been reported to dealer but will occur in coming days. There were no prior symptoms, problems, or warning lights on dash display prior to this occurring.

The contact owns a 2018 Cadillac XT5. The vehicle was recently purchased, and while driving at an undisclosed speed, the vehicle failed to accelerate as intended while depressing the accelerator pedal. In addition, the vehicle failed to accelerate above 5 MPH with several unknown warning lights illuminated. The dealer was notified and sent a mobile mechanic to the residence to diagnose the vehicle; however, no cause for the failure was found. The vehicle was towed to the dealer, and it was diagnosed that the emission starter module had failed. The dealer reprogrammed the emission starter module. The contact stated that a week after the repairs were performed, while driving at an undisclosed speed, the vehicle sputtered, and the failure persisted. Several unknown warning lights were illuminated. The dealer was notified of the failure. The vehicle was not inspected or diagnosed due to the cost. The contact stated that the failure persisted, and the vehicle failed to start. The vehicle was no longer able to be started. The contact stated that the vehicle was repossessed but was recovered. The vehicle was towed to the residence and had not been driven since. The manufacturer was not notified of the failure. The failure mileage was approximately 2,000.

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 (FOIA), 5 U.S.C. 552(B)(6)

Brakes failure. Approaching a busy intersection and facing a red light, I slowed and prepared to stop the vehicle. Nothing happened with regard to braking; instead, the engine seemed to rev up as it continued through the red-lighted intersection with 2 lanes of busy cross traffic from both directions. That there was not a collision is a miracle. I also noticed some flashing displays on the display screen, though hard to take time to read them while avoiding a crash and still trying to stop the car, but I believe they referenced "parking assist." My husband came and drove the car to the dealership (about 3 mi.), and during that drive, there was no braking issue but a Parking Assist readout suddenly appeared, and he was able to return the screen to the map; then a few minutes later, while driving under 20 mph near the dealership there was a notice about "maximum speed" being reached and "parking assist" being somehow reactivated. Vehicle currently at dealership for analysis. Side note: this is our second Cadillac to exhibit this problem -- there should be an NHTSA report on the first (April 2025) -- a 2013 SRX, in which there was a parking lot collision that totaled the vehicle.

The contact owns a 2018 Cadillac XT5. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently lost motive power. The contact was able to coast to the shoulder of the roadway, where the vehicle failed to restart. While attempting to restart the vehicle, the vehicle required several attempts before restarting. After the vehicle was restarted, the vehicle returned to normal functionality, but the failure became a regular occurrence, prompting the contact to discontinue driving the vehicle. No warning lights were illuminated. The vehicle was taken to an independent mechanic, who was unable to determine the cause of the failure. The vehicle was not repaired. The manufacturer was notified of the failure but provided no assistance. The contact was advised to take the vehicle to the dealer for assistance. The failure mileage was 40,000.

While waiting at a light, then the car shut off. Lossing all power. I could not get out of the vehicle, no hazards, no lights, nothing. After several pulls of the door handle I was able to open the door but the hazard light was not able to come one. After 4 attempts to engage break to push start the vehicle on ethe brake locked up and would not disengage. Total screen black out, no power no hazards. After some time, the brake released screen activated and I was able to press the brake and try to start the car again. It did not work but was now able to turn on hazards. After 15 mins, I tried again and it cranked up normal. I had new battery in June 2025 and 60K Maintenance services in Aug 2025. This happen in Oct 2025.

The contact owns a 2018 Cadillac XT5. The contact stated that while stopped at a stop light, the front driver's side seat independently moved forward and backward. The contact stated that the driver's side rearview mirror independently folded inwards. No warning lights were illuminated. The contact stated that the failure was persistent and scary. The contact stated that during the failure, the driver's seat independently moved forward, and the contact was pushed up to the dashboard. The contact stated that when the front driver's seat independently moved backwards, the contact was pushed to the rear of the vehicle, and the foot failed to remain on the brake pedal. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The manufacturer was not made aware of the failure. The failure mileage was unknown.

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

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

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.

My 2018 Cadillac XT5 has a serious water intrusion issue—water is leaking into the interior cabin through the sunroof or roof seams. This appears to be the result of a known manufacturer defect covered in GM’s Technical Service Bulletin TSB 19-NA-167. The leak has caused significant water accumulation on the floor, raising concerns about mold, electrical failure, and corrosion. I brought the vehicle to a Cadillac dealership, and they confirmed the issue. The total repair estimate is around $7,900. Cadillac offered partial goodwill coverage, but I am still being required to pay $3,400 plus tax out of pocket. I have authorized the repairs but am seeking reimbursement for the portion Cadillac is not covering, as this is not normal wear and tear—it is a clear defect in manufacturing that poses safety and health risks. GM should be fully covering this issue for affected vehicles.

Engine thermostat defective, which causes the computer to speed up radiator fans, and causes temperature gauge to read zero. Dealer replaced under warranty at 68,000 miles and same problem reoccurred at 90,000 miles. Common problem on Cadillac XT5’s (all years)

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.

Rear toe arms are malfunctioning barely drive vehicle on 54342 mileage on vehicle. Having to do with steering jeopardize Leicester on my and my family. VMy vehicle has been inspected. This issue has been inspected by Cadillac mechanics and indicated needs immediate attention. No indicator lights were illuminated to inform me of danger. I am impalled about this situation and I shouldn’t be charged for this mechanical default.

I received a Steering Assist is Reduced message and the cooling fan ramped up to full speed. In contacting Cadillac, it seems that it is a below temperature error for the thermostat. Unsure what the thermostat has to do with steering. Also in researching this, this is a wide spread issue and needs to be a recall. My XT5 has 48000 miles on it and the powertrain warranty expired 3 months ago. I believe this should be a recall and should be repaired by the manufacture as it could cause a safety issue while driving.

The contact owns a 2018 Cadillac XT5. The contact stated that while driving at slow speeds, the vehicle unintendedly shut off. The vehicle was towed to the local dealer who diagnosed that the body control module (BCM) had failed and needed to be replaced. The contact was informed that BCM failure was caused by internal corrosion to the unit due to condensation leaking from the HVAC water line, which was positioned above the BCM. The vehicle was repaired. The contact stated that the BCM unit was previously replaced due to the same failure. The manufacturer was notified of the failure. The failure mileage was 95,000.

The coolant thermostat was broken and gave two check engine codes P0128 and P0128P. AC was not functioning when the thermostat was not working, which can be dangerous in summer. It is also a very common problem with Cadillac XT5 and GMC Acadia.