Can You Drive Far With A P0128 Code Mercedes Benz

It’s a lot of fun to drive a car. Sometimes you just don’t want to stop when you are on a long drive. However, what if your car disagrees and has other plans? As you are speeding on the highways, in your Mercedes Benz, you notice the P0128 code.

Now, what can you do? Do you continue driving or attend to the issue in the middle of nowhere? If you decide to drive, how far can you drive with the P0128 code on?

What Does P0128 Code In Mercedes Benz Mean?

In a Mercedes Benz when the code P0128 comes up, it means the coolant’s temperature is below the optimal thermostat regulating temperature. If you notice your coolant gauge, there will be an indication of the optimal temperature. This is the temperature your engine should be at when running. 

All engines will have a coolant, which circulates through the engine’s bay forced through by the water pump. As it circulates and reaches the engine, it will absorb the heat from the engine (that is generated when the engine is running). Now, this coolant becomes hot and flows to the thermostat sensor and valve.

The thermostat sensor will read the liquid and pick up data required for the car’s computer and feedback. The valve will simultaneously regulate the coolant’s flow. How much a valve opens is directly proportional to how hot the coolant is. The valve will open more is the coolant is hotter, to let the heat pass. 

After passing through this valve, the hot coolant will next reach the radiator where it will be cooled down. The is a large amount of air hitting the radiator when the Mercedes breaks the air resistance and speeds, this air will in turn cool the coolant in the radiator.

When this process does not happen so smoothly, the coolant temperature fluctuates, resulting in code P0128.

Reasons For Code P0128

Some of the possible reasons for the code P0128 are:

  • A broken thermostat valve that is unable to regulate the coolant temperature as expected
  • The thermostat is open and stuck 
  • The wiring of the coolant temperature circuit has gone bad
  • The radiator fan is running continuously
  • Broken down sensor that could be giving out false reading, thus causing the code

Signs To Watch Out For

Here are a few signs you may notice in your car before the code P0128 shows up:

  • Check engine light goes on while driving
  • The vehicle takes longer time than usual to warm up
  • Idle is higher than the normal range
  • Fuel efficiency decreases (you may be filling in fuel more frequently)
  • The temperature shown on your vehicle’s temperature gauge is lower than normal

If you notice any of the above, it is an indication that your engine is not functioning at its optimal level. You need to get it checked and sorted out if you don’t want to wear down your engine sooner than anticipated.

The Distance You Can Travel With P0128 Code Mercedes Benz

It is not advisable to drive too long if the coolant reading is too low. The optimal running temperature of your vehicle regulates many things. When the car engine is running at the optimal temperature, the oil gets heated to the right level and becomes viscose. Only after this can it circulate through the engine smoothly.

The engine takes a considerable amount of time to reach this temperature. The car’s computer knows that and supplies fuel accordingly. This is why initially when you start the engine, the fuel consumption will be more and it will gradually decrease as the engine runs. 

Now, when the engine reading is still low or cold, the computer perceives it as the engine just started, so it supplies more fuel. Thus increasing your fuel consumption.

This increased supply of fuel will continue until the optimal temperature is reached. When the thermostat valve is broken, it’s hardly likely to happen. As a result, more fuel will be injected continuously, resulting in more deposits and residue and loss of power.

If You Keep Driving With Code P0128 – What Can You Expect?

Now, if you are stuck somewhere with the code P0128, you can definitely drive for many miles. You can even opt to continue driving with the code on. However, under the hood of your vehicle, the engine and all other surrounding parts are struggling and wearing out. Not attending to this in time can become an expensive affair.

The more you push your engine to function without controlling the temperature, the earlier it will wear out and give trouble. The sooner you get to address this issue, the better it will be for your engine’s life.

Can I Drive With Code P0128?

If you are already on a road trip and have nowhere to get your car checked, you can continue driving to the nearest fuel station and get the vehicle checked. 

If you notice the code before you take off on your long journey, it is advisable to have it fixed before you leave. Driving too long with the code P0128 might cause your engine to overheat and break down when you least expect it. you may be forced to wait until the radiator and the engine cools down before you can continue with your journey.

Also, your car will be consuming more fuel, thus making the trip much more expensive than you anticipated.

Fix The Code P0128

So, how can you fix the code P0128 in your Mercedes Benz? 

You have to first replace the thermostat valve. If the temperature does not regulate even after that, you might have to replace the sensor that is reading the coolant temperature. A problem with the sensor is not common, so the valve is always repaired or replaced first. Touch the sensor only if the code persists.

Mechanics might tell you they will assess the issue and only then touch a car like Mercedes Benz and won’t replace parts unnecessarily. However, for some issues, you need to rule out possibilities before you can narrow down the problem. It is a safer bet to replace the thermostat valve instead of touching the sensor right away.


The engine is a well-designed mechanism that keeps your car running despite all odds. When well taken care of and attended to, you may not have any issues.

The warning lights and codes are designed for a reason and you need to adhere to them if you want the best out of your car as promised by the manufacturer.

Liam Dare

As CEO of, my passion for the automotive world motivates me to build online businesses that provide information and entertainment to users. I am proud to contribute in a positive way to the automotive community.