KNOWN FAULTS · Smart

Smart fortwo / forfour (453) EQ / electric drive common problems.

2014–2024 · Electric

Sources are not verified in real time and no entry confirms that your car is affected.

3 known faults with sources

Single clunk from the rear drive shaft when moving off or changing direction (smart and Mercedes-Benz)Transmission

Engine / equipment: smart fortwo and forfour 453 and Mercedes-Benz cars with rear drive shafts
Period mentioned: 2014 onwards
Symptoms: A single sharp clunk at a rear wheel when moving off or switching from reverse to forward (or the other way round); it makes no noise while driving.
Possible cause described: Micro-movement or a cracked micro-weld between the wheel bearing inner race and the drive shaft's outer joint housing. Mercedes-Benz technical note LI35.30-P-058566 fixes it by coating that contact surface with Molykote paint.
Check for the garage: Tell the garage it is a single clunk when changing direction; the technical note says to test by loosening the drive shaft nut by one turn (it is always replaced with a new one).
Cost cited in the source: No verified estimate; ask the garage for a quote.A rough figure from the original database, not an up-to-date quote.

smart EQ (453) range that drops suddenly or battery that will not charge, from a voltage difference between cellsHigh-voltage battery

Engine / equipment: smart fortwo and forfour EQ / electric drive (453)
Period mentioned: The whole electric 453 series
Symptoms: The range shown does not match the charge, drops very quickly after a short trip, or the high-voltage battery no longer charges. Possible codes: P0DE616 and P0DE717 (cell voltage too low or too high).
Possible cause described: The voltage difference between the highest and the lowest cell of the high-voltage battery is too large (over 100 mV) because a cell self-discharges; in extreme cases the battery management system no longer shows the cell voltages. It is described in Mercedes-Benz XENTRY technical note LI54.10-P-069138.
Check for the garage: Take it to the dealer soon: they read the cell voltages with the diagnostic equipment and assess whether it can be transported (the self-discharge gets worse with time). The fix the brand gives is replacing the high-voltage battery. Never handle the high-voltage system.
Cost cited in the source: No verified estimate; ask the garage for a quote.A rough figure from the original database, not an up-to-date quote.

Applies if: Weak points of this model from inspections, breakdown statistics and recalls; anything specific to one engine is stated in the sheet.

12 V battery, brakes and campaigns on the smart 453 (EQ too)Known weak points

Engine / equipment: smart fortwo and forfour 453 (petrol and electric EQ)
Period mentioned: 2014–2024
Symptoms: A flat 12 V battery on 2015–2016 cars (no lights-on warning); at inspection, suspension, rusting brakes and lights (and on petrols, oil leaks and a rusty exhaust); electronic faults (radio, a pedal sensor that upsets the stop-start); on the forfour, an emergency-call assistant that does not work.
Possible cause described: CarWiki rates the technology as very reliable. Recalls (KBA): the link between the P selector cable and the gearbox, a handbrake cable nut that could come loose and front steering knuckles that could break due to a manufacturing fault.
Check for the garage: Test the 12 V battery; brake hard now and then (especially on the EQ); check campaigns by VIN.
Cost cited in the source: No verified estimate; ask the garage for a quote.A rough figure from the original database, not an up-to-date quote.