IsItAGoodCar

Common Problems with the
2008–2014 Smart Fortwo (451)

We've identified 3 known issues that can affect the 2008–2014 Smart Fortwo (451). 2 of these are serious faults that could be expensive to repair.

3
Known Issues
2
Serious
1
Moderate
0
Minor

The 2008–2014 period has 1 more issue than the Smart Fortwo (451) average across all year periods.

All Known Issues

MHD Drive Belt Failure

SeriousEngine

The Mild Hybrid Drive system uses a belt to start the engine and drive the water pump. If the belt snaps, the engine will overheat almost instantly, often warping the head.

Most affected: 71bhp Non-turbo MHD models

Estimated cost: £200 (belt) to £2,500 (engine rebuild)Affects: 2008–2014Often appears around: 15,000–40,000 miles (between changes)

Typical symptoms

  • •Battery light on dash
  • •Engine temperature warning
  • •Sudden loss of power

What to inspect before you buy

  • ✓Ensure the "Modified" belt kit and tensioner have been installed (Service Campaign work)

SAM Unit Corrosion (Water Ingress)

SeriousElectrics & Electronics

In the UK, water can enter the cabin via the door seals or heater intake and track down to the SAM unit (located in the passenger footwell).

Most affected: All RHD models

Estimated cost: £500–£1,000Affects: 2007–2014Often appears around: Any age

Typical symptoms

  • •Lights coming on by themselves
  • •Dead battery
  • •Non-start issues

What to inspect before you buy

  • ✓Check for moisture under the passenger side carpet

Clutch Actuator Failure

ModerateGearbox & Transmission

The actuator that operates the clutch can seize or wear out, leading to jerky gear changes or failure to select drive.

Most affected: All automated manual models

Estimated cost: £300–£600Affects: 2007–2014Often appears around: 40,000–70,000 miles

Typical symptoms

  • •Jerky pull-away
  • •Slow gear changes
  • •Car stuck in neutral with "3 bars"

What to inspect before you buy

  • ✓Listen for a "creaking" noise from under the car when the ignition is turned on

Buying Tips for the 2008 Smart Fortwo (451)

  • ✓On MHD (Mild Hybrid Drive) models, check that the starter-generator belt and tensioner have been updated to the latest revision.
  • ✓Test the air conditioning thoroughly; the pipes are prone to chafing and leaking refrigerant.
  • ✓Look for evidence of "clutch teaching" or adaptation in the service history to ensure smooth shifts.
2007 Smart Fortwo (451)

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Other Smart Fortwo (451) Year Periods

20072008–2014

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