Mercedes-Benz S400 Tire Pressure Warning Light Stays On

Common Causes for the Tire Pressure Warning Light in Your Mercedes-Benz S400 and How to Resolve Them

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Reviewed by
Devin Cabugcal
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 Mercedes-Benz S400 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 Mercedes-Benz S400 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.

Troubleshooting Tire Pressure Warning Light in a Mercedes-Benz S400

When faced with a tire pressure warning light in your Mercedes-Benz S400, the first step is to check the tire pressure. Use a reliable gauge to ensure that each tire is inflated to the manufacturer's recommended levels, as incorrect pressure is a common cause for the warning light. If the pressures are correct, the next step is to reset the Tire Pressure Monitoring System (TPMS). This can typically be done through the vehicle's central display settings, where you can find the TPMS reset option. If the warning light remains illuminated after these initial checks, it may indicate a deeper issue, such as a malfunctioning sensor or damaged wiring. In this case, a thorough inspection of the TPMS sensors and their connections is necessary to identify any faults. Should these steps not resolve the issue, it may be time to consult a professional mechanic who can provide a more detailed diagnosis and repair. By following this structured approach, you can effectively troubleshoot the tire pressure warning light and maintain the safety and performance of your vehicle.

Why is the Tire Pressure Warning Light Staying On in a Mercedes-Benz S400?

When the Tire Pressure Warning Light remains illuminated in your Mercedes-Benz S400, it can be a source of concern, but understanding the common problems can help you address the issue. One of the primary reasons for the warning light is incorrect tire pressure; both over-inflation and under-inflation can trigger the system, so checking and adjusting your tire pressure to the manufacturer's specifications is essential. Additionally, tire damage or punctures can also cause the light to stay on, so visually inspecting your tires for any visible signs of wear or damage is a good practice. If you notice uneven tire wear or experience a rough ride, it may indicate that the tire pressure needs reactivation, which can often be done through the vehicle's onboard system. Furthermore, issues with the Tire Pressure Monitoring System (TPMS) sensors themselves can lead to persistent warning lights; if the light is flashing, it may suggest a malfunction that requires sensor replacement. Regular maintenance, including monthly tire pressure checks, especially during seasonal temperature changes, is crucial for optimal vehicle performance and safety. By being proactive and informed about these common issues, you can effectively manage the tire pressure system in your Mercedes-Benz S400.

Why is the Tire Pressure Warning Light Staying On in a Mercedes-Benz S400?

When the Tire Pressure Warning Light remains illuminated in your Mercedes-Benz S400, it is crucial to take immediate action. Ignoring this warning can lead to unsafe driving conditions, as incorrect tire pressure can significantly affect vehicle handling and increase the risk of tire blowouts. Over-inflated or under-inflated tires not only compromise safety but can also lead to uneven tire wear, resulting in costly replacements. Additionally, if the light persists due to tire damage or a malfunctioning Tire Pressure Monitoring System (TPMS), you may face further complications, including reduced fuel efficiency and increased repair costs. Regularly checking your tire pressure and addressing any underlying issues promptly will not only enhance your driving safety but also prolong the life of your tires and vehicle. Therefore, it is essential to investigate the cause of the warning light and take corrective measures without delay.

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