Three lines on the dash indicate a 'Gearbox communication fault' or a 'Shifting system fault'.

Firstly it could just be a glitch... they do happen. Turn the car off and on again and see if the issue is resolved.

Other potential issues could be:

• Sticking clutch actuator
• Faulty or sticking gear selector motor
• Faulty gear position sensor
• Excessive clutch wear
• Loose/broken connection to the actuator/motor/sensor
• Damaged wiring where the loom passes under the intercooler duct

For a quick fix, you can try:

• With engine off and handbrake off and in reverse, rock the car backwards and forwards to free up the gears. Lubricate the gear actuator - see the guide on this site - replace gear selector motor, replace gear position sensor (we also have a guide for this) located in the fortwo gearbox page.

If you experience 6 dashes flashing in the mileage display, it is usually accompanied by a flashing fuel gauge display, and a flashing temperature gauge.

It would indicate a communication fault from your ECU or SAM unit, so firstly, check these cables.

It could also indicate:

• SAM and ECU are not correctly paired
• Water damage in the SAM unit

The resolution, if it's not loose wires, would be to replace the SAM unit and pair it to the ECU. Sadly this is not a cheap option, but it is a fairly serious fault.

Fast flashing indicators is usually attributed to a blown indicator bulb on that side.

If they only flash fast when indicating left, then check the indicator bulbs on that side.

It might be that the connection of one of the bulbs is weak, whether in the bulb holder or the wiring to it.  To rectify you can either replace the lamp cluster or wire in a new connector.

We have also noticed and issue with LED indicator bulbs where these cause a resistance issue which may also lead to the bulbs flashing at a double rate. You can either wire in an additional resistor, but to be honest, you might as well just remove the LED bulbs and replace with conventional ones.

Normal running temperature for the Roadster is or 80-85 degrees. It should reach this temperature within 10-15 minutes of normal driving. Note - your Roadster will need to be fitted with dash pods in order to see the water temperature. We consider pods to be a essential addition.

If on normal motorway journeys your car sits below this, then this will be one of 2 things:

• Thermostat sticking open
• Faulty temperature sender

We have a guide on here to allow you to change the thermostat,  and the temperature sender is located on top of the thermostat. If you change the thermostat, you will get a new sender with it.

If you find your car is overheating, this can be one of a few things to look for:

• Thermostat sticking closed
• Airlock
• Faulty temperature sender
• Faulty water pump
• Head gasket failure
• Alternator belt failure

We have a guide for replacing the thermostat on here, and it will come with a new sender.

A simple airlock can really affect the temperature.  If you have recently bled the system and/or changed the coolant, this could be the problem. Follow our coolant change guide to re-bleed the system. 

A water pump failure can cause a lot of serious damage.  It is located at the front of the engine and driven from the alternator belt.  After checking that the belt is all still in place, you will need to lower the engine to give better access for changing the pump.

In some circumstances a head gasket failure can cause the hot gases to be pushed into the water cooling channels.  You will probably see an oil residue in the water, possible a milky residue on the oil cap, and will more than likely cause the engine not to run properly.

If there are no lights on the dashboard and no error codes, but the car still feels sluggish, it can be one of a number of things, all easy to check and rectify:

• Intercooler pipe has popped off
• Wastegate arm as come loose
• Crankcase breather pipe split/popped off
• Cycle valve failure

To check the intercooler pipes, open the engine bay, and just pull on both pipes!  If you get any movement then the pipe has popped off, commonly either on the turbo, or the turbo pipe to the intercooler... rarely would it be the intercooler to throttlebody pipe.

The 'E' clip which secures the wastegate arm onto the wastegate pivot might as well be made of chocolate. They corrode very quickly, and the arm will drop off, meaning that the wastegate flaps open and all of the gasses bypass the turbo.  Push the arm back on and replace the e-clip, though temporary fixes can be made with paperclips/hair clips.

The crankcase breather has a valve to stop the charged air from going down into the crankcase, but if this pops off (from the throttle body) then the boost is vented to air, usually with a splash of oil too! Simply replace the pipe or reconnect and secure with a hose clip.

Cycle valve failure: this can be checked using a winstar/star which can manually operate the valve to check its functionality. Replacement of the valve is fairly easy to do by yourself though.

Black smoke indicatees that your car is running rich: it's over-fuelling. Alongside the black smoke you'll probably be experiencing terrible fuel economy.

The reasons for overfuelling could include:

• Over-zealous remap (some remaps deliberately over-fuel for more power)
• Air restriction/blockage
• Faulty IAT or MAP sensor
• Faulty/failed fuel pressure regulator

If you have recently had a remap, and are only just noticing the excessive smoke, then it might be advisable to try a different remap. Some remaps deliberately overfuel to create more power. This can cause more problems in the future as it tends to wash the oil film from the cylinder bores leading to compression loss and piston ring failure.

Probably the easiest job is to check the airbox for leaves/restrictions!  Restricting the airflow can lead to a mixture difference resulting in over-fuelling.

Faulty sensors can provide false readings and cause the ECU to over-fuel, but diagnostics on a star/winstar should be able to read these.

A faulty fuel pressure regulator could allow greater fuel pressure through the injectors during their duty cycle, again causing over-fuelling. The regulator is easy and cheap to change.

Hearing a knock when at slow speeds can indicate that the suspension bushes are wearing. These are only about £5 each; alternatively an entire wishbone assembly is only about £30.

It could also be:

• Top mount nut loose
• Ball joint failure
• Engine mount failure

If the top mount is loose, then re-tighten or replace - however these are done up very tight so I would investigate as to why it is loose in the first place.

If the engine mount is worn/failed the knocking will be more prominent under acceleration but you will still hear knocking when going over bumps.

9 flashes indicates that the key fob battery is low... there is a guide on here to assist you.

In slightly rare cases, if the indicators flash continuously or randomly (or the car fails to respond), it could also indicate that the key fob has just or is about to lose synchronisation with the car. Unfortunately you cannot stop this, just get your spare ready and prepare to go to a independent smart specialist or main dealer - someone with access to a STAR machine - to have the key re-synchronised.

The noise can be attributed to one of a couple of things:

• Snapped front coil spring
• ABS ring splash plate not located correctly

If you look at the spring (can be either the top or the bottom of the spring), you will see a broken or missing section, the car will also sit slightly down on one side. The only solution is to replace the front spring (change them both at the same time!). There is an internal recall (service order) at smart to deal with this very well known problem, it's code is SO38. Phone a dealership to see if you are eligible for a free replacement.

If the springs are both okay, and the noise is a little more 'tinny' it could be that the backing plate for the front hub is mis-aligned, which causes the brake disc to *just* touch the plate under turning. Remove the front wheel, and relocate the backing plate.

All smarts that are equipped with the service indicator will display when the next service is due. This can be viewed by double tapping the display button as follows:

• fortwo 450: Double press the button on top of the dash.
• Roadster: Double press the middle button on top of the dash.
• fortwo 451: Double press the button to the left of the dash.

By default, this will display the distance the car has to travel before the service is due. The type of service will be either an 'A' or 'B' indicated by 1 or 2 spanners respectively. When service time approaches, the electronics will indicate that a service is due by displaying the distance left to go when you start the car. This screen will then revert to your previous display mode (outside temperature / trip / total distance covered).

However, the smart must also be serviced every year. So, if the distance hasn't been reached, the service counter will switch to the number of days left until the service is due. This will then count down each day.

If a service hasn't been performed by the time the counter reaches 0, the countdown will continue into negative numbers, e.g.: '-10' = Ten days overdue for service.

In order to make this change you will need to visit your local smart dealer or a mechanic with a STAR machine. The car needs connecting to smart specific diagnostics in order to make this change.

'Bunny hopping' will occur with a badly adjusted clutch actuator. To resolve this, you should try a manual adjust of the clutch actuator followed by an electronic adjust using a STAR machine available at most independent dealers.

If the problem gets worse and the car seems to 'slam' into gear, then either your clutch or clutch actuator is on its way out and will require replacement. Be careful not to run the car too long this way as you can risk fracturing the clutch mounting plate.

The temperature sensor is located inside the left engine air vent next to the fuel filter. It looks like a spike that sits in the air stream into the engine. Because of this, the temperature is not very accurate. You may have noticed on occasions when you start your car again after a drive the temperature is higher than it should be. This is because the heat from the engine radiates across the sensor giving a misleading figure. As soon as you start driving again, the outside air temperature is measured as it is sucked into the engine which can result in a slightly lower reading.