Category: 452

Can I fit a baby seat in my Smart Car?

Yes, however Forward facing child restraint systems may only be fitted to the front passenger seat if it is moved to its rearmost position.

*safety note potential hazard item*

Where is the Smart car battery located?

The battery can be located under the carpet beneath the area where the passenger foot well, you need to ensure all electrical devices are off, lift the carpet and remove the foot support (usually secured by 2 fasteners) by sliding it out of the car sideways, first unscrew the negative then the positive terminal.

*safety note potential hazard item*

When driving my Smart car slowly I get a weird spring sensation through the brake pedal and a noise to accompany it?

Have someone check the ABS reluctor rings (they are at the end of each rear driveshaft), these corrode and split over a period of time making the ABS not work when it should be, the split rings give incorrect signals to the ABS sensors that in turn makes the ABS pump unit work when it is not required.  Fit new driveshafts or have a qualified person replace the ABS timing rings.

*safety note potential hazard item*

My Smart car Roadster interior door handle does not work, why?

There is a cable and on the end is a barrel pin that locates in the door mechanism, this works its way out, usually there is nothing broken it can be refitted and secured to reduce the chance of it happening again.

I have heard dump valves are good on turbo engines, can I fit one to my Smart?

No, it is not recommended, as there is a formula for determining the size of the aperture in the dump valve. Thus, most dump valves simply dump too much boost for the Smart instead of preventing the turbo 'stalling' (stopping as boost backs up in the system as the throttle is shut), it dumps too much boost causing the turbo to over speed risking damage to the turbo bearings.

Why are Smart car engines worn out so quickly?

Firstly lets get this into perspective. A 61bhp 599cc car is making 101.83 Bhp per litre which is very impressive, and the same specific power output as an E36 BMW M3. It is a little engine with only 2.7 litres of oil to cool and lubricate it. Most are driven flat out, full throttle everywhere, and often undergo poor maintenance. For example: sometimes only 3 spark plugs have been changed (they have 6: two per cylinder), they are given the the wrong oil and low grade fuel. There are many examples running high mileages and achieving 55+ mpg, but these have had a gentler life. Smart state in the handbook "Normal operation at constant speed 2000-3000rpm, brief periods of acceleration, e.g. when passing 3000-6300rpm."

I have a performance exhaust on my Smart car and my engine light has come on, is the exhaust faulty?

No not necessarily, the smart car has set parameters for all the engines settings, by changing them from standard you run the risk of the engine management unit thinking there is a problem.  Changing any part of the car can cause this but exhausts and air filters are most common.

NB. You can buy a unit that fits between the exhaust and lambda sensor that alters the reading reducing the chance of the engine light coming on.

Why is my Smart car having trouble selecting gear?
It could be one of several things: 1. Check the rear lights to see if the brake lights are working; if not then it's probably the brake light switch which is faulty and needs replacing. (On a 450 it's between the under tray and the car chassis and it helps to have the car on a ramp. On a 452 or 454 it's under the brake pedal in the foot well.) 2. Then the wiring to the gear selector motor needs to be checked to see if there is damage to the wiring causing electrical short circuits 3. Check the clutch actuator adjustment and operation 4. The clutch unit may be worn and need replacing, always replace the release bearing at the same time
The heating fan in my Smart car roadster is not working, why? [452]
Most likely it’s the connection to the switch itself, they seem to have a poor connection there and the connection arcs and burns away the metal in the switch unit. It needs repairing, sometimes a piece of wiring loom and connector are required and sometimes the central console unit will also need to be replaced
Why does my Smart car have 3 little lines in the centre of the dash?
Usually 3 lines relates (shifting system fault) to a electro/mechanical problem with gear selection rather than a signal control problem see gear selection Q and A
How much oil do I need in my roadster? [452]
3 litres
My Smart Car’s handbrake travel is very high, why?
It's probably the rear shoes and adjusters that need cleaning and adjusting properly, these usually get done about every 4th year - it could be the rear wheel cylinder seals have failed and are weeping brake fluid. A competent garage can remove the rear hubs and clean and inspect the cylinders and replace and adjust as necessary.
Why does my Smart car have 1 little line in the centre of the dash?
1 Can bus malfunction - the line usually indicates a system fault usually a signal or communication error, this really needs to have diagnostics run by someone experienced with a star machine and Smart Car knowledge.
My car is using a lot of oil but I can’t see any smoke – is it burning it?
It depends on how much is being used up: If it’s more than 500ml per 500 miles or 1L per 1000 miles then yes, the engine may be on a downward spiral. It’s likely that the oil control rings are gummed in place by carbon, allowing excess oil to enter the combustion chamber and be burnt in the normal combustion process. The temperature inside the turbocharger unit is high and the oil is almost always evaporated by the time it gets to the exhaust and the catalytic converter, so you rarely see smoke on a hot engine. Monitor accurately the oil consumption and the miles covered and contact us to discuss options. It will consume more oil until one of the following two things will happen, and there is no cheap fix for either one  1. An exhaust valve will burn away as the engine will be running extra hot when low on oil and the oil burning much hotter than just fuel - this usually causes the engine to go onto two cylinders, it will have very little power and will sound strange 2. If maintenance has been sporadic the next thing to go will be a spark plug, the electrode will overheat if the oil is to low or oil will cover the plug and foul it - either way it will misfire.
I heard a funny “Twang” noise from the front of my car, do I need to worry?

Yes, the noise could be the top of one of the front coil springs shearing. Did you find an inch long piece of black/rusty semi-circular metal nearby? The front end of the car suffers all the crashes and bangs you too feel from the car’s suspension. The springs seem to rub in the top cup causing damage just as it locates in the top cup. Over a period of time this gets worse until the spring shears off. NB always have both replaced and always and change the top mounts as the design has been changed. They are usually replaced in pairs. *safety note potential hazard item*

My Smart car battery is flat can I bump start it? [452]
Yes, see section 10 32 of the 452 manual. This is the procedure from the manual for the 450 / 452 always make sure it is safe to do so ,*safety note potential hazard item* Turn ignition to position 1 Put the handbrake on Press the footbrake and hold Hold the gear lever in the forward + position Release the footbrake Press the accelerator to the floor (while stationary) Release the handbrake and start rolling (you need a good shove though or steep hill) Once moving the clutch will automatically engage and the engine will start
When I accelerate in my Smart car I get a whistling noise that goes up and down with the revs, why?

It sounds like the turbo has a damaged inner part, the impeller blades can spin up to 2000 times a SECOND and any damage to these special blades will make a whistling noise.

My key won’t unlock the car, is the battery in the key fob low? [452]
It could be. It's more likely that the key has fully discharged, lost its coding and will have to be re-coded along with the car and any spare keys you might have. Try to use both keys equally and often to prevent losing the coding. There has been no satisfactory explanation as to why they do this. If the battery is low the indicators will flash 9 times quickly (indicating you can use it 100 times more - so change the battery asap). When changing batteries observe correct polarity and change them promptly. Batteries are available in many retail outlets and garages. The battery size is CR1225. See the handbook for how to replace the battery.
When I change gear in my Smart car there is a little ‘Ptchew’ noise I can hear, is something wrong?
Well, if the boost level is increased or a free flowing air filter fitted you will hear this noise, it the sound of the boost in the turbo being released as the throttle is closed.
Can I just replace the valve that's burnt out in my Smart car?

Applies to 452 450

Answer: No it will burn out very quickly, it would be like putting a plaster on a broken leg, the problem will happen again (as quickly as 3 weeks, we have seen very unsatisfactory repairs), the only satisfactory option is to replace or get a professionally rebuilt engine. The condition of the bores and the pistons and rings may determine if the engine will need a rebore and new pistons

My Smart car radio says “SAFE” or “CODE” what do I have to do to get it working again?
If the head unit doesn’t work and the display reads SAFE or CODE, then the memory has been lost (usually after a battery disconnect) and the anti-theft protection is activated. The display should show "SAFE" or "CODE" then revert to four dashes after 3 or 4 seconds at power on (if you haven't put a code in recently). Enter your code at this point (when the 4 dashes are shown), then press the smart symbol button to confirm the code. The radio should be activated. Example - if your code is 4321 you would get the 4 dashes to show and then press the "1" button x4 four times, the "2" button x3 three times, the "3" button x2 twice times and the "4" button x1 one time. It’s a bit like text messaging using 1 button for multiple options. Then press the Smart symbol button once after all digits are correct. If you get it wrong, the unit will go into a wait state showing SAFE again (not allowing any more input) for an increasing time (starts at 20 seconds or so ) , you can do this up to 7 times by which time the wait period before it lets you re enter a code is 24 hours before you can put another sequence in - using the 4 station pre-sets. If you don’t have a code or it's not correct then you need to apply to a main dealer for a radio code, V5 registration docs and ID will be required usually and a fee usually about £30 depending on each dealer.
My Smart car battery is flat can I bump start it? [454]
Yes, see section 9 36 of the forfour manual. This is the procedure from the manual for the 450 / 452 always make sure it is safe to do so *safety note potential hazard item* Turn ignition to position 1 Put the handbrake on Press the footbrake and hold Hold the gear lever in the forward + position Release the footbrake Press the accelerator to the floor (while stationary) Release the handbrake and start rolling (you need a good shove though or steep hill) Once moving the clutch will automatically engage and the engine will start
My car (petrol) is going very slow, like it has no turbo boost, what’s wrong?

First thing to check under the rear of the car is the waste gate arm, it's held in place by a tiny E clip and these can rust and fall off meaning no boost will be allowed at this point. Be careful as the exhaust is very hot and you need a clip to be able to fix it. *safety note potential hazard item* Secondly, if the car is standard get the car diagnostics checked. It could be the cycle valve, check the hoses to it and if it needs to be changed then check the boost pressure sensor (look at the reading to determine if boost is produced or not). In the case of remapped cars it could have gone into safe mode (a get you home mode which uses much less power). *safety note potential hazard item*

My Smart car won’t start and it shows a little key symbol in the centre of the dash, why?
The immobiliser is still on. It turns itself on automatically after 60 seconds if you have not started car after unlocking it. Remove the key and unlock the car again. Then, replace the key and start as normal. See next section.
My Smart car key unlocks the car but won’t turn off the immobiliser, why?
It likely the key has lost its coding (9 indicator flashes should accompany this when pressing the key fob unlock or lock button if it's faulty) and will have to be re-coded along with the car and any spare keys you might have too. They all will have to be taken to someone with a Star Diagnostic machine to re-code them all together. Its worth getting an additional new key before so you can get it coded at the same time, if you don't already have a spare key.
My paddle steering wheel is not working properly. It does not change gear on one side properly or it is intermittent, what might be causing this?
It's probably the steering wheel angle sensor which has failed, these cannot be bought separately, only as a whole steering wheel. The problem needs a diagnostic machine to verify, if this is the case a new steering wheel is the answer. The car looks to the steering wheel angle sensor to see how much steering input you have when deciding how to brake safely in an emergency. Safety note: the ABS and ESP may not work properly in an emergency if these are faulty.
Can I tow my Smart car (452)?
Yes, see section 10- 34 of the of the manual. The ignition must be switched on. If the car is being towed, **the gearshift lever must be set to position N and the dash read N for neutral or you risk terminal engine damage** If you have had gear selection problems do not tow. *safety note potential hazard item* Towing notes: Only people with a certain amount of experience should tow. A metal tow pole is the best option *safety note potential hazard item*
My steering is stiff, someone said it might be my power-steering? [452]
Yes, it could be your electric power steering, they can work intermittently causing the steering to be easy or difficult as the power steering goes on and off again, clean and check the electrical terminals and check the wiring if it continues it may require a new power steering and rack. *safety note potential hazard item*
Can I just replace the valve that's burnt out in my Smart car?

Applies to: 450, 452

No it will burn out very quickly, it would be like putting a plaster on a broken leg, the problem will happen again (as quickly as 3 weeks, we have seen very unsatisfactory repairs), the only satisfactory option is to replace or get a professionally rebuilt engine. The condition of the bores and the pistons and rings may determine if the engine will need a rebore and new pistons.