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Mercedes C-Class owner’s guide

If you’re the proud new owner of a Mercedes C-Class, you’re in for many miles of effortless motoring. This compact luxury car comes loaded with features and equipment to keep you entertained and comfortable on the move.

With so many on-board functions, however, it might not be immediately obvious how they all work. This guide will explain how to use your C-Class, along with how to respond to any warning messages and lights that might flash up.

How to open the bonnet of a Mercedes C-Class

Mercedes C-Class, how to open bonnet. Left image shows red tab in driver's footwell, right image shows metal tab under bonnet.
First, pull the red tab in the driver's footwell, then lift the metal catch in the bonnet gap

You might want to open the bonnet if you need to top up your screenwash or check your car’s fluids. Thankfully, this is easy on the C-Class. Before you begin, make sure the engine's off and has fully cooled down.

First, find the little red lever on the underside of the dashboard in the front passenger's footwell (the front-left seat). Pull this lever to unlatch the bonnet.

Once you've done this, go round to the front of the car and slightly lift the bonnet with one hand. A little to the left of the badge in the middle, you should be able to feel a catch with your other hand that you can push with your fingers.

Press the catch and lift the bonnet. Once you've lifted it a short way, the struts will take over and push it the rest of the way, holding it in place while you access the engine. Once you're done, push the bonnet closed again – it shouldn't take much force but make sure you press it firmly enough that you hear the latch click to lock it into place.

How to turn on AC in a Mercedes C-Class

Mercedes C-Class, how to turn the AC on. Climate controls shown with arrows highlighting main features.
'AUTO' turns the automatic climate control on or off, 'A/C' toggles air con on or off manually

All Mercedes C-Class models come with fully automatic two-zone climate control, which you can activate by pressing the 'AUTO' button on the front centre console. This lets the car work out how much AC or heater to use to maintain a steady, comfortable temperature.

On the centre console, use the red/blue arrow buttons on the left or right to choose your desired temperature for the car's left and right sides. You can also press the 'SYNC' button to set both sides at the same time just using the driver's side arrow button, if you want the whole car to be the same temperature.

If you want to adjust your own AC settings without using the automatic climate control, press the 'A/C' button on the centre console, which toggles air conditioning on or off. This will override the automatic climate control settings.

For new C-Classes built from 2022 onwards, all the above instructions remain the same. The only difference is the climate control buttons are now found exclusively at the bottom of the MBUX infotainment screen. Auto climate control, temperature, fan speed and window defrosters are all permanently displayed, and you can access more detailed functions by pressing 'Climate menu'.

What are the correct tyre pressures for a Mercedes C-Class?

Mercedes C-Class, what are the correct tyre pressures. Tyre pressure sticker inside fuel filler with arrow highlighting it.
Find the sticker inside your fuel filler flap to see the correct tyre pressures for your C-Class

The C-Class comes with several different wheel options, each with a specified pressure setting. You should also increase the pressure if your car is fully loaded with passengers and cargo.

To locate the correct pressure settings for your car, find the card with the pressure information. On C-Classes, this is printed on the inside of the fuel-filler flap. This card will give you several pressure options for different wheel sizes and load options – i.e. whether you're just carrying a passenger or two and a little cargo, or fully loaded.

You can check which is the correct pressure for your car by locating the tyre size code printed on the side of your tyres. Common sizes for C-Class cars include 225/50R17 or 245/40R18, but your code will closely resemble these if it doesn't match them exactly.

Find the same code on the tyre pressure card, then select the pressure depending on whether you're carrying a normal load or a full load. Pressures may be written in PSI (pounds per square inch), bar or kPa (kilopascals), so make sure you're using the correct units when selecting your pressure setting.

How to turn on media in a Mercedes C-Class

Mercedes C-Class, how to turn on media. Stereo controls on centre console with on/off switch circled.
Press the on/off button in the centre console to turn on your infotainment system

Media in your C-Class such as radio or Bluetooth audio will usually start playing automatically once you start the car if you left the media on the last time you drove it.

To fully activate or deactivate the C-Class' infotainment system, you can use the 'on' button – a ring with a small vertical line in it – that's located in between the front seats.

You can also mute and unmute the infotainment system by using either of the volume controls, found on the steering wheel and in between the front seats. These are rotary controls that let you adjust the volume but you can press them down to instantly mute or unmute the system.

How to check AdBlue level in Mercedes C-Class

Mercedes C-Class, how to check AdBlue level. Side by side showing the service menu in the instrument binnacle then the AdBlue selection.
Select 'Service' in the driver's screen, then click on 'AdBlue' to see your current AdBlue level

Diesel-powered C-Classes are equipped with an AdBlue system. This injects a fluid containing urea into the exhaust to clean out some of the harmful pollutants before they make it into the environment.

C-Class cars carry a little more than 20 litres of AdBlue, which should be enough for between 10,000 and 15,000 miles. Your AdBlue should get checked and refilled every time you service your car, so it's possible you might never have to refill it yourself.

However, if the car has flagged up a low AdBlue level, or if you just want to check it, you can do so through the screen in the driver's instrument cluster. Press the home button on the steering wheel then, using the scroll arrows on the left side, navigate to 'Service' and press the 'OK' button. Once there, navigate to 'AdBlue' and click 'OK' again – this will show you a graphic of how much AdBlue is left and what your predicted range is.

How much AdBlue does a Mercedes C-Class need?

Mercedes C-Class, how much AdBlue. Driver's screen showing current AdBlue level.

Most diesel-powered C-Class cars come with an AdBlue tank that carries around 25 litres. This is usually enough to cover a 10,000 to 15,000 service interval. The AdBlue filler is located next to the diesel fuel filler under the flap.

If the car has warned you that you're running low on AdBlue, we'd suggest avoiding completely filling the tank as there's a risk you might overfill it and splash the fluid over yourself or the car's components. You're better off buying a five-litre top up, for example, and then getting your service centre to properly top the tank up at the next service.

How to reset AdBlue warning in a Mercedes C-Class

Mercedes C-Class, how to reset AdBlue warning. AdBlue filler shown next to fuel filler.
The AdBlue warning should reset once you refill the tank – the filler is found under the fuel flap

Your C-Class will flash up a warning message in the instrument cluster if it detects that the AdBlue is running low. You'll need to refill the AdBlue tank to clear this message.

Your car should detect automatically when you refill the tank, but you might need to drive it around for several miles for the car to realise and the message to clear. If the message doesn't clear, take it to your local service centre or Mercedes dealership to get checked.

How to reset engine management light in a Mercedes C-Class

Mercedes C-Class, how to reset check engine light. Startup warning lights shown, check engine light highlighted.
If the engine management light comes on while driving, you should take your car to a service centre

If your Mercedes C-Class has flashed up an engine management light – also known as a check engine light – the safest thing to do is to arrange for it to be checked by a Mercedes dealership or your preferred service centre. Ignoring a warning light, or resetting it without fixing the problem that triggered it can cause serious damage to your engine or other components, leading to costly repair bills.

If, however, you want to clear the engine management light to see if it comes back on – providing a clearer indication of an ongoing problem – you can do so by disconnecting the car's battery:

  • First, open the bonnet and find the battery cover – this is usually at the back left side of the engine bay.
  • Then remove the plastic cover on top of the battery by turning the finger screws that hold it down and gently pulling it away.
  • This will expose the battery and its two terminals.
  • Disconnect the cable clamped onto the negative terminal – you'll need a wrench and socket to do this.
  • Hold the cable to the side, away from the battery terminal and other components – do not let it touch any parts as this could cause sparking. It helps to have a second pair of hands to do this.
  • With the cable held aside, turn on the headlights or press the horn to drain any power that remains in the car's system.
  • After 60 seconds and with the power drained, reconnect the battery.

This will reset the engine management light. At this point, you should take the car for a drive. If the light doesn't come back on, then the issue is resolved but, if the light comes back on, you almost certainly have a problem that will need diagnosing by a qualified repair specialist.

It's worth noting that a common cause of engine management lights is failing to securely screw down the fuel filler cap. The car will detect the loss of pressure in the system and flag up a warning light. Correctly tightening the cap and driving for a short while should see the light reset itself.

How to reset tyre pressure warning in a Mercedes C-Class

Mercedes C-Class, how to reset tyre pressures. Left image shows service screen, right shows tyres selection.
First select 'Service' in the driver's screen, then click on 'Tyres'

Your C-Class will flag up a warning message if it detects that your tyre pressures are low. Once this happens, you should use a tyre pump to refill your tyres to the correct pressure. You can purchase home-use pumps powered by your car's 12V socket, or find an air pump at most petrol stations. You can use the chart printed on the inside of the fuel filler flap to tell you what tyre pressures you should be using.

After you've refilled your tyres, you'll need to reset the tyre pressure warning. This can be done by pressing the home button on the steering wheel to bring up the menu in the driver's dials. Using the arrow keys on the wheel, navigate through this menu to 'Service' and press 'OK'. In the Service menu, you will see 'Tyre pressure' – navigate to this option and press 'OK'.

Mercedes C-Class, how to reset tyre pressures. Left image shows tyre pressure, right shows reset screen.
Your current pressures appear in the Tyres menu after a short drive. Swipe down for the reset menu

You'll either see the tyre pressures displayed, or a message saying pressures will be shown after a few minutes of driving. On this screen, press the down arrow, which will bring up an option to 'Use current pressures as reference values' – press 'OK' to confirm this. The car will then display a message letting you know that pressures will be shown after a few minutes of driving so take the car for a short spin and the system will reset, clearing the tyre pressure warning light.

How to turn on fog lights in a Mercedes C-Class

Mercedes C-Class, how to turn on fog lights. Fog lights button highlighted.
The fog light button is next to the headlight switch to the right of the steering wheel

Mercedes C-Class cars built from 2015 onwards no longer have front fog lights thanks to improvements in headlight technology making them no longer necessary.

C-Classes still include a rear fog light, which you can activate using a button on the lighting panel. This panel is found near the driver's right knee, slightly below and to the right-hand side of the steering wheel, and contains the main rotary switch for the headlights. The fog light button can be found on the left of this rotary switch.

More handy guides

Now you know your C-Class from bumper to bumper, why not improve your skills on the road too? Check out our handy guides on what to do if your car starts skidding, how to safely drive in fog, and our tips to quickly demisting your windscreen.