Mercedes C Klasse ABS and Steering Problems

Multiple system failures linked to a tire pressure warning is unusual, but not impossible. The TPMS relies on sensors in each wheel. A faulty sensor could trigger the initial warning, but the ABS and power steering issues are likely related to the pressure loss itself, especially if it's significant. The decreased tire circumference on the affected wheel throws off the wheel speed sensors, which can freak out the ABS. The increased steering effort is a direct result of the underinflated tire. Have you checked for any damage to the tire sensor itself? Or perhaps tried swapping the wheel with the spare to see if the symptoms subside? Also, are you certain it's only one tire that's low? Double-check with a different tire gauge just to rule out a faulty gauge reading.

Good point about the wheel speed sensors potentially causing the ABS issue. I hadn't thought of that. I haven't specifically checked the tire sensor for damage, I'll have to take a closer look. As for swapping with the spare, that's a good idea, I'll try that tomorrow. And yes, I am certain it's only one tire that's showing low pressure. I did double-check with another tire gauge, and both confirmed the same reading. What exactly should I be looking for when inspecting the tire sensor? Are there any telltale signs of damage or malfunction?

When inspecting the tire sensor, look for physical damage first – cracks, breaks, or corrosion. If it's an externally mounted sensor, check the valve stem for leaks by applying soapy water and watching for bubbles. If it's internally mounted, you'll need to dismount the tire to inspect it properly. Given the cascading failures you're experiencing, and the fact that you've verified the low pressure with two gauges, it's highly likely the low tire pressure is the root cause, stemming from either a valve issue, damage to the tire, or the sensor itself. I'd advise against driving the vehicle in its current condition, as the compromised ABS and steering could be dangerous. I suggest visiting a reputable workshop to diagnose and resolve the problem. They can perform a thorough inspection of the tire, wheel, sensor, and related systems.

Thanks for the advice. I appreciate the insights, especially regarding the wheel speed sensors and the potential impact on the ABS. I took your advice and brought it to the workshop. Turns out it was indeed a defective valve in the tire, causing a slow air leak. They replaced the valve and the tire sensor as a precaution, and that seems to have fixed everything. Total cost was around 280€. The ABS light is off, the steering is back to normal, and the tire pressure warning is gone. Thanks again!