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Ross, Diagnostic and repair technician
Category: Car
Satisfied Customers: 1183
Experience:  Licensed diagnostic and repair technician
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We have a Smart Car ForTwo 05 plate which has around 100,000

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We have a Smart Car ForTwo 05 plate which has around 100,000 km on the clock. Whilst driving along at low speeds on country lanes just lately the car appears to stall. This has happened to both myself but more importantly to my wife when the car came to an abrupt halt - fortunately no vehicle was behind her. The car restarts after opening, closing, locking and unlocking the car.
On all occasions the car has been at least half full of fuel.
My wife loves the car but I feel she is getting anxious.
All advice welcome.
Hello and thanks for trusting me to help you today. I am a licensed diagnostic and repair technician, I look forward to working with you.
This usually comes down to one of three possible causes, firstly is the engine earth lead, this can corrode which causes high resistance and a poor earth connection which can cause the engine to cut out. It's worth checking the contact is clean on the earth before going any further but I suspect this is not the problem in your case. The next possibility is an ECU software issue which effected some models, there is an update available which needs to carried out by a main dealer to upgrade the software on the engine control unit to prevent this problem.
Finally is the crankshaft position sensor, this I suspect is the most likely cause... Locking and unlocking the doors will not effect the sensor but they generally restart after 15 seconds or so, locking and unlocking the doors may simply be giving the sensor enough time to cool down and restart. I Suspect the sensor is going faulty, generally they cut out when hot and will restart after several seconds
Customer: replied 2 years ago.

Hi Ross,

On my last occasion I had only left the house by less than 500 yards when the engine dashboard light came on and the car stalled, fortunately about 30 yards before a T junction.

Ok, if the engine management light comes on, it is a sigh of a sensor causing the problem. It is a good sign as this means there will be a fault code stored in the control unit so the next step is to have the car plugged in to a diagnostic scanner which will give a readout of the fault which will usually pinpoint the cause. There are many possible causes so it's best to get it scanned before speculating at causes, crank sensor would still be my first suspect.
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