Mercedes Gear Change Delay – What Are the Common Reasons?

If your Mercedes delays gear change, it could be because of a cold engine, sport mode, or problems with the transmission such as low fluid or bad pressure. Also, this can happen when the ECU doesn't get an overall understanding of what's happening in the engine - so some sensors don't work or give bad readings.

Transmission shifting delay problem highlights

• Level of importance:Medium
• Reasons:Low fluid, overheating, torque converter problems
• Needed expertise:High
• Needed tools:Depends on the reason
• Time taken:1-8 hours
• Can you drive? Carefully
• Possible issues: Fatal transmission failure, torque converter damage.

What do you need to notice when Mercedes delays changing gears?

It's important to understand what exactly happens to your car when gears don't shift at the needed time. So, let's check that we are on the same page.

You get into your Mercedes, start the engine, and drive. Suddenly you notice that the engine is rotated up to 3000-3500 RPM, the car vibrates and the sound of the engine is unusually loud. Why does the transmission hold to lower gears and doesn't shift as it usually does - somewhere near 2500 RPM?

You should stop panicking and notice such important things:

• What is the exact RPM when your transmission changes gears?
• Is there something you changed in the settings of the car like applying a different transmission mode?
• Is the engine temperature OK? Or is the engine still very cold?
• What was the last time you maintained the transmission? Oil and filter changes are required regularly (but not as often as with the engine oil).
• Do you see any warning lights or error messages when the problem with your transmission is happening?
• Does it all come back to normal after you drive for a while?

Also, you may try to notice if the engine power is OK. It may be that the vehicle went to limp mode which means it will lose some power and the behavior of the transmission will greatly change. But finding the actual reason for this problem is not that easy. One good thing is that your Mercedes will tell you about going to limp mode by throwing a certain message.

So, after you notice all the symptoms that accompany the strange shifting behavior, you are ready to locate the problem. Chances are you may even do this on your own, without paying several hundred dollars to the dealership.

What are the common reasons for shifting delays in a Mercedes vehicle?

Now, when you are calm and trying to figure out all the symptoms, you may need to know about the actual reasons that trigger this problem in your Mercedes. Shifting issues almost always make us think that the problem is with the transmission and the repair may cost a couple of thousand but the reality may be much more positive.

Here are the most common reasons you should check:

1. You applied Sport or Manual modes in the transmission

A lot of Mercedes cars have a manual shifting mode and paddle shifters under the steering wheel. If you turn on the manual mode, it won't just stay in the first gear all the time. The transmission will still shift but it will allow you to do it on your own. It may shift at 4000-5000 RPM (when it's not good anymore for the engine to hold on to the lower gear).

Also, you may have unintentionally turned on the Sport mode. In this mode, the transmission will shift much later than usual. It will shift well after 3000 RPM to allow you to accelerate faster and get great emotions when driving. You may be surprised, but these are the most common reasons why your Mercedes may delay shifting gears.

2. Low transmission fluid or poor pressure

It's not uncommon for Mercedes automatic transmissions to develop issues with leaks or fluid contamination. This may cause problems with shifting because the fluid is one of the most important components of the conventional automatic transmission.

If the fluid pressure goes down, the transmission may not shift gears at all or may shift them too late. Unfortunately, checking the fluid level in a modern automatic transmission is not that easy and you will most likely need to go to the dealer or to any good independent shop. There is no dipstick in the majority of Mercedes transmission models.

Make sure you change the transmission fluid and filter as often as the driver's manual says. Otherwise, the problem with the bad or contaminated fluid will be there in your car, sooner or later.

3. Clutches wear

The clutches in automatic transmissions are absolutely different from the clutches in manual ones. But they still may go bad and slip. This will trigger the so-called limp mode in the transmission and it may start shifting later.

I wouldn't say this is the most common problem for a Mercedes automatic transmission. But you should keep it in mind because a high-mileage transmission may throw such a surprise on any day and you should be ready.

4. The engine and transmission are cold

When the outside temperature is low, it's highly recommended to warm up the engine for at least one minute. This allows the thick and cold oil to come through all the passages and start lubricating the engine properly. Also, the transmission fluid may become much thicker when it's cold.

To warm up the transmission, you may put it to D or R when the engine is warming up. Make sure you press the brake pedal all the time when warming up the transmission. After that, you may drive and the problem should disappear. Also, it will disappear on its own once the engine and the transmission are warmed up on the go.

5. Low battery voltage

Your engine and transmission are controlled by advanced electronic control units. These depend largely on the voltage in the system. If the voltage drops sharply, the units may fail and develop a glitch. Then, they will throw random messages and warning lights and turn on limp modes without any serious reason for this.

When sitting, your battery should show 12.4-12.5 volts. The voltage shouldn't drop too low when you are cranking the engine. Also, when the engine starts, the voltage on the battery terminal should go over 14 volts due to charging system work.

If you notice any deviations, it's likely that the battery needs replacement or at least recharging.

6. Electronic issues

I won't describe a lot here because any engine or transmission sensor may lead to gear-shifting problems. This means that the system went to limp mode and is now working in a special mode to prevent failing. Just run an inspection with a good OBD2 scanner and find out what's triggering this lump mode in your Mercedes.

7. Software glitch

Although Mercedes vehicles don't often develop problems with software, they sometimes can do this. And the problem with shifting gears may be one of the consequences of such an event. If you experience this, you may want to reset the electronic control modules and later I will explain to you how you can do this.

Can you solve the problem on your own?

There is not much you can do without professional inspection and proper scanners. But if your Mercedes is not under warranty anymore, you can try several things:

1) First check the transmission mode

If the transmission is not in the normal mode, fix this and see if the shifting pattern changes.

2) Warm up the engine and the transmission

If this is happening when the engine and the transmission are still cold, it may be OK. Wait till the units are warmed up and see if the problem disappears.

3) Reset the control units

You may do this by disconnecting the 12V battery for 5-10 minutes. Disconnect the negative terminal, then the positive one. Wait for several minutes and then connect the positive terminal and after that the negative one.

4) Use the OBD2 scanner

If you have the scanner, use it and read the codes. You will most likely get an idea of what's happening with the vehicle.

5) Go to the shop

If you can't locate the problem but the transmission keeps freaking out, immediately go to the dealership or an independent shop. Your Mercedes needs proper inspection and repairs.

Can you drive if your transmission shifts too late?

If your transmission shifts too late in a Mercedes vehicle, you still can drive. But it doesn't mean that you can ignore the problem. Maybe, this is a limp mode and you need to get to the dealership as soon as possible.

Anyway, you should know more about the reasons for this problem and only after that you can keep driving. Without this, you will likely get issues with your Mercedes transmission and will have to replace it, in the end. This will cost you much more than a small repair that your transmission may require right now.

Anyway, if you decide to drive in such a condition, you should be absolutely careful on the road. Anything can happen, so don't drive too fast and be ready for any behavior of your car!