Hard Steering & ABS Issues Point to Power System Trouble

As someone with moderate experience working on similar issues, I actually had this exact problem with my 2001 Buick LeSabre, very similar car to yours. The symptoms you describe match my experience almost perfectly. In my case, it turned out to be a defective tire valve causing gradual pressure loss. The flat tire led to the ABS warnings and steering issues because the car was trying to compensate for the uneven tire pressure. The tire monitoring system was correctly warning about pressure loss, but the root cause wasnt immediately obvious. The workshop found that the valve was letting air leak slowly, causing the tire to lose pressure over time. The total repair cost was 280 Euro, which included replacing the faulty valve and a full system check. Before going to a workshop, I recommend checking: Current pressure in all tires, Signs of uneven tire wear, Whether pressure loss happens in one specific tire, If the ABS warning changes after reinflating tires To help diagnose this better, could you share: Which tire shows low pressure? How quickly does the pressure drop? Have you noticed any punctured tire signs? Does the steering wheel shake more at certain speeds? This information would help determine if youre dealing with the same valve issue I had or if theres something else going on.

Thanks for the previous replies. After 173101 KM on my Buick, I can add some details that might help diagnose this: The front right tire loses pressure significantly faster than others, dropping about 8 PSI every 2-3 days. After inflating all tires to proper pressure this morning, the steering improved briefly but then got worse again. The wheel shake is most noticeable between 45-60 mph. The tire monitoring system keeps alerting even after filling the tires. I also noticed the front right tire shows uneven wear on the inner edge, and the pressure loss seems to be getting worse over the past few weeks. There are no visible signs of a puncture, but the constant pressure loss in that specific tire seems to trigger all these other issues. Based on the responses so far, I will have the valve stem checked first before looking into bigger problems.

Thanks for the additional details about your Buick. Based on your description, I am even more convinced this matches the valve issue I dealt with on my LeSabre. The pattern of pressure loss you describe, 8 PSI every few days in the front right tire, is remarkably similar to what I experienced. The constant pressure loss and uneven wear strongly point to either a faulty tire valve or potentially a damaged tire sensor. When my tire monitoring system kept alerting after refills, it was because the valve stem was cracked, causing a slow but persistent air leak. A quick way to confirm: spray soapy water around the valve stem and watch for bubbles. This test revealed my leak quite clearly. Some points worth noting: Uneven inner edge wear often indicates alignment issues, which can worsen when running on an underinflated tire, The speed range where you notice vibration (45-60 mph) matches typical symptoms of pressure loss, The tire sensor may need recalibration after fixing the leak I suggest having both the valve stem and tire sensor checked, as they often work as a single unit on these models. The consistent pressure loss pattern makes me fairly certain youre dealing with a similar valve issue to what I experienced.

Thanks everyone for helping me understand this better. After monitoring things for a few more days, I wanted to share what happened: The constant pressure loss in my front right tire definitely seems to be the root cause. I tried the soapy water test suggested and saw bubbles forming around the valve stem. The tire monitoring system alerts have been consistent with this, showing the most pressure loss in that tire. I scheduled a repair appointment specifically asking them to check the valve stem and tire sensor unit first. The hard steering and wheel shake got noticeably worse when the tire pressure dropped, it would improve temporarily after inflating the tires but then deteriorate as pressure decreased again. The uneven wear on the inner edge still concerns me, so I will have them check the alignment too once the pressure loss issue is fixed. Makes sense that driving on an underinflated tire could have affected the alignment over time. Really helpful to know others have dealt with similar valve stem issues in these models. At least now I can point the shop in the right direction instead of paying for unnecessary diagnostic work. Will update once its fixed.