So the run flat indicator light came on in your Mercedes. Don’t panic! This handy guide will walk you through everything you need to know to reset that pesky little light and be back on the road in no time.
Here’s a quick guide:
To reset a Mercedes run flat indicator when it illuminates, first check all tire pressures and repair any leaks to restore PSI to the door jamb’s recommended level. Then use a tire pressure monitoring system reset tool connected under the dash, or find the instrument cluster menu for tire pressures, holding the reset button for 10+ seconds until the light turns off. Finally recheck pressures after a few days of driving to confirm proper calibration.
What is a Run Flat Indicator?
First things first – what exactly does that run flat indicator light mean? Well, many modern Mercedes models come equipped with a run flat indicator that monitors air pressure levels in your tires. It’s designed to alert you if one or more of your tires is significantly under-inflated or flat.
This allows you to take action before serious tire or wheel damage occurs from driving on a flat. The light itself looks like a yellow or red car with a squiggly line under it. Some models may also show a specific tire pressure value.
When Does the Light Come On?
The run flat indicator typically illuminates if tire pressure drops 25% or more below the recommended level. So if your tires are supposed to be at 32 PSI, the light would come on around 24 PSI or lower.
The drop in pressure could be due to:
- A small puncture
- A valve stem leak
- Natural loss of pressure over time
The light may also malfunction and come on due to a faulty sensor.
Dangers of Driving With the Light On
While your Mercedes is designed to safely drive up to 50 miles after a loss of tire pressure, it’s not a good idea to ignore that run flat light for long.
Driving on severely underinflated or flat tires can lead to:
- Permanent tire damage
- Reduced braking ability
- Poor vehicle handling
- Potential wheel damage
So if that indicator pops on – take action ASAP!
How to Reset the Run Flat Indicator Light
Resetting the pesky run flat indicator requires a few simple steps. Here is the complete process:
Step 1: Address the Underlying Issue
Before resetting the light, you’ll want to find and fix the root cause of the air loss. Here’s how:
- Locate the problematic tire – Use an accurate tire pressure gauge to check all tires. Identify any reading significantly lower than recommended.
- Examine tire for damage – Closely inspect the low tire inside and out for cuts, punctures, or any damage. Mark the location of leaks if found.
- Repair or replace – Small punctures can usually be patched from the inside. For larger damage, the tire will need replacement.
- Properly inflate – Fill all tires to the manufacturer recommended PSI printed on a sticker inside the driver’s side door jamb.
Step 2: Reset the Light
Once all your tire pressures are set correctly, you are ready to reset that pesky indicator light!
The exact reset procedure varies a bit by Mercedes model and year, but generally follows one of these options:
With a Tire Pressure Monitoring System (TPMS) Reset Tool
- Connect the reset tool’s cable to the special port under your dashboard, often near the pedals
- Turn on the ignition, with the engine off
- Press and hold the reset button on the tool for 3+ seconds until the light blinks or turns off
Via the Instrument Cluster Controls
- Use your keyfob or key to turn on electrical power without starting the engine
- Find the buttons that scroll through and adjust the instrument cluster displays
- Navigate to the tire pressure menu
- Hold down the reset or “OK” button for 10+ seconds, until the values reset to zero and the light turns off
That’s it! The run flat indicator should now stay off as long as your tire pressures remain at the recommended PSI.
Step 3: Recheck Tire Pressure
I recommend rechecking all tire pressures again after 2-3 days of driving. It’s common for pressure to drop again after a repair as the tire seals. Simply reinflate as needed.
You may need to drive briefly prior to the final pressure check to allow the tire pressure monitoring system to recalibrate and clear any error codes.
And voila! You have successfully reset your Mercedes’ run flat indicator light. No need to panic next time that pesky light comes on – just follow this guide to get back up and running in no time.
|Run Flat Indicator
|Yellow or red warning light that monitors tire pressure
|When It Illuminates
|If pressure drops 25% or more below recommended PSI
|Dangers of Ignoring
|Tire damage, poor handling, reduced braking, potential wheel damage
|Address underlying issue, refill tires to proper PSI, use TPMS reset tool or instrument cluster controls to reset light
|Recheck pressures after 2-3 days of driving
I hope you found this guide helpful for understand what that run flat light means, when you should worry about it, and all the steps needed to get it reset properly. Let me know if you have any other questions!
1. My tire pressure is normal but the run flat light is still on – what should I do?
If the light remains on even after properly inflating your tires to the recommended PSI, the tire pressure monitoring system sensor likely requires recalibration. Try driving the vehicle for 10+ minutes above 25 mph to give the sensors time to recalibrate, then recheck all pressures. If the light remains on, use a TPMS reset tool or the instrument cluster menus to manually reset the light.
2. How can I tell which Mercedes tire is causing the run flat light to activate?
Many Mercedes models display individual tire pressure values on the instrument panel or infotainment screen. Compare these readings – the one showing significantly lower pressure is likely the culprit. You can also use a high quality individual tire pressure gauge to check each one.
3. What could cause the run flat light to malfunction or come on randomly?
Faulty tire pressure monitoring system sensors are the most common reason for incorrect or random run flat warnings. The batteries in these sensors wear down over time. Replace suspected failing sensors one at a time until the light resets properly with normal tire inflation.
4. Is it safe to drive with the run flat light illuminated?
Mercedes indicates it’s safe to drive up to 50 miles with the run flat light on. However, driving on significantly underinflated tires can lead to tire, wheel, alignment, and brake damage over time and is not recommended. Have it checked ASAP.
5. Will using Fix-a-Flat or an inflator kit cause the run flat light to turn on?
It’s likely that adding sealant or inflator chemicals into your tire will set off the indicator light due to residue interfering with tire pressure sensor readings. Follow the reset procedure to clear these error messages and indicators after using temporary tire repair products.