2018 Mercedes-Benz S450 Tire Pressure Warning Light Stays On

Resolve the Persistent Tire Pressure Warning Light in 2018 Mercedes-Benz S450

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Reviewed by
Andrew Hajjar
Written by RepairPal Car Genius
Updated January 14, 2025
0%
40% chance it's the
Tire Leaking Air
0%
30% chance it's the
Wheel Leaking Air
0%
15% chance it's the
Tire Pressure Monitoring System
0%
15% chance it's
Something else
The most common reasons a 2018 Mercedes-Benz S450 tire pressure warning light stays on are a leaking tire, a wheel that no longer holds air, or a faulty tire pressure monitoring system.
  • Tire Leaking Air: A puncture, valve stem issue, or rim damage can cause a tire to leak air, leading to loss of pressure.
  • Wheel Leaking Air: A puncture or damage to the tire or rim can cause air to leak, resulting in a loss of tire pressure.
  • Tire Pressure Monitoring System: A malfunctioning tire pressure monitoring system can be caused by faulty sensors or a dead battery in the sensor units.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2018 Mercedes-Benz S450 tire pressure warning light stays on?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

When a tire pressure monitoring sensor fails, the tire pressure monitoring system control module will recognize a loss in communication and turn on the warning lamp which indicates the failure. This is most often the case. However, the tire pressure monitoring sensor may also fail by reporting incorrect tire pressures. This could cause a flat tire to go unrecognized, or a properly inflated tire to signal a low or high tire pressure warning.

When a relearn is needed, for any reason, the TPMS warning light will illuminate, and many vehicles will display a message relating to the TPMS system being inoperative or loosing communication. It is important to keep a watchful eye on tire pressures when this system is having issues because there is no warning available for underinflation or overinflation of the tires.

Wheels offer very few symptoms, but these symptoms should never be ignored. Visible cracks on the wheels may appear, especially after hitting a large bump, Most often, this will also be accompanied by loss of air from the tire on that wheel. Also, vibration in the steering wheel is very common when the tire is out of balance, and improper wheel nuts or bolts can cause creaking and popping noises to develop. Again, there are very few symptoms, but they should not be ignored.

The only symptoms of a TPMS control module failure are failing to alert the driver of underinflation or overinflation of one or more tires, failure to communicate with the body control module or TPMS sensors, or erroneously reporting incorrect tire pressure.

The only symptoms requiring diagnosis for the tire pressure monitoring system warning lamp is if the warning lamp has illuminated while the tires have correct air pressure, or if the air pressure for the tires is out of specification and the warning lamp is off. This is because the overwhelming majority of cases where the TPMS lamp illuminates is due to the change in ambient temperature.

What are the initial steps to diagnose a tire pressure warning light that stays on in a 2018 Mercedes-Benz S450?

When faced with a tire pressure warning light that remains illuminated in your 2018 Mercedes-Benz S450, the first step is to manually check the tire pressure in all four tires, including the spare. Using a reliable tire pressure gauge, ensure that each tire is inflated to the manufacturer's recommended levels, as improper inflation is a common cause of warning lights. Next, inspect the tires for any visible damage such as punctures, cuts, or bulges, which could indicate a loss of pressure. If the tires appear to be in good condition, attempt to reset the tire pressure monitoring system, as this can sometimes clear false warnings. Additionally, examine the valve stems for any signs of wear or leaks, as faulty stems can also lead to pressure loss. If the warning light persists, consider using a diagnostic scanner to check for fault codes related to the tire pressure monitoring system, which can help identify more complex issues. Finally, consulting the vehicle's owner's manual can provide specific troubleshooting steps tailored to your model, ensuring you have all the necessary information to address the problem effectively. By following these steps, you can systematically diagnose and potentially resolve the tire pressure warning light issue on your own.

What could be causing the tire pressure warning light to stay on in a 2018 Mercedes-Benz S450?

When the tire pressure warning light stays on in a 2018 Mercedes-Benz S450, it can indicate several common issues that DIYers can troubleshoot. The first step is to check the tire pressure in all four tires, as low pressure is the most frequent cause of the warning light. If the pressure is within the recommended range, the next potential issue could be a faulty tire pressure sensor, which may need replacement. Additionally, the sensors might require recalibration to ensure they are providing accurate readings. Electrical faults within the tire pressure monitoring system can also lead to the warning light remaining illuminated, which may necessitate more advanced diagnostic skills to identify and fix. Lastly, performing a system reset can sometimes clear the warning light, and this procedure is usually detailed in the vehicle's manual. If these troubleshooting steps do not resolve the issue, it is wise to seek assistance from a certified mechanic or dealership for a comprehensive inspection and repair.

What immediate steps should be taken to address the tire pressure warning light on a 2018 Mercedes-Benz S450?

When the tire pressure warning light activates on your 2018 Mercedes-Benz S450, it is essential to respond swiftly to mitigate safety risks and prevent potential vehicle damage. Neglecting this warning can lead to serious consequences, including reduced fuel efficiency, uneven tire wear, and the risk of tire blowouts, all of which can compromise your safety on the road. Begin by checking the tire pressure of all four tires using a reliable gauge, ensuring that the readings align with the manufacturer's recommended levels, which you can find in your owner's manual or on the sticker located inside the driver's door jamb. If you find any tires are underinflated, promptly inflate them using an air compressor or a portable tire inflator. Additionally, conduct a thorough inspection of each tire for any visible signs of damage, such as punctures or bulges, as these may necessitate tire replacement. After addressing any pressure issues or damage, remember to reset the tire pressure monitoring system, typically accessible through your vehicle's onboard menu. By taking these immediate actions, you not only enhance your safety while driving but also contribute to the overall performance and longevity of your tires.

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