2018 Smart Forfour problems
The 2018 Smart Forfour was sold with 2 engines that we have documented: the 0.9 TCe and the 1.0 SCe (B4D). The 0.9 TCe has serious faults that affect the cars of that year. The safest option is the 1.0 SCe (B4D) (verdict “With caution”).
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2018 Smart Forfour score: good reliability
Calculated using only 9 documented faults and their sources: the most serious and frequent faults weigh more. How it is calculated
- Engine6.4From 5.1 to 7.7 depending on the engine
- Gearbox10.0No documented faults
- Suspension7.0Technical inspection (ITV) only: 1.2 times the defects normal for its age
- Brakes7.7Technical inspection (ITV) only: 0.9 times the defects normal for its age
- Tyres and wheels10.0No documented faults
- Steering7.0Technical inspection (ITV) only: 1.2 times the defects normal for its age
- Electrical system10.0No documented faults
- Headlights and lights6.5Technical inspection (ITV) only: 1.4 times the defects normal for its age
- Electronics and infotainment10.0No documented faults
- Climate control10.0No documented faults
- Bodywork and interior8.0Technical inspection (ITV) only: 0.8 times the defects normal for its age
- Airbags and safety10.0No documented faults
What changes compared with the 2017 Smart Forfour
- Score: 6.4 → 7.8
- No longer affected by: front left hub carrier with insufficient strength (2017 campaign) (rest of the car) and 12 V battery: a common reason for roadside assistance on 2015 to 2017 Forfours (rest of the car)
0.9 TCe engine in the 2018 Smart Forfour
- With caution
0.9 TCe 90 (H4Bt, 2012-2024)
90 hp · H4Bt-400, H4Bt-408, H4Bt-410
The reliability record is positive and better than that of its sibling the 1.2 TCe, without the oil consumption or rate of chain problems so well documented for that engine. Check the coolant history (leak at the thermostat housing) and, to a lesser extent, any history of noise or work on the timing chain before buying.[3][4]
Faults that affect 2018 cars
- High severityFrequency: CommonCoolingCoolant leak at the thermostat housingThe 0.9 TCe can lose coolant through the thermostat housing (calorstat) gasket. It is the most-cited fault of this engine: if not detected in time, the low level can end up damaging the head gasket.
- Critical severityFrequency: OccasionalTimingTiming chain or tensioner failureThe 0.9 TCe's timing chain tensioner can lose effectiveness over time. It is a minority of cases, but when the chain jumps the damage is serious: there is a documented case with a complete engine replacement at 80,000 km.
- High severityFrequency: RareTurboTurbocharger wear or failureThe 0.9 TCe's turbo can lose performance or fail, although the available statistics put it as an infrequent fault on this specific engine.
- Low severityFrequency: RareInjectionJerking due to an injection calibration that needs reprogrammingSome 0.9 TCe engines show slight jerking when accelerating because of an injection calibration that is corrected by reprogramming the ECU, without it being mechanical damage.
- Low severityFrequency: RareLubricationOil consumption (uncommon on this engine)Unlike other engines in the same family, the 0.9 TCe does not show a widespread pattern of excessive oil consumption: the sources document only a minority of cases.
1.0 SCe (B4D) engine in the 2018 Smart Forfour
Names: 1.0 52 kW (71 CV)
- With caution
1.0 SCe 70/75 (B4D, 2014-2024)
70–75 hp · B4D
No serious or systemic fault is documented in the reliability sources consulted (117 combined reviews across the three cars). It is worth checking the clutch, with a pattern of slipping or juddering when cold cited independently on the Dacia Sandero II, the Dacia Logan II and the Renault Twingo III, and, in the specific case of the Sandero II, keeping an eye on oil consumption.[5][6][7]
Faults that affect 2018 cars
- Medium severityFrequency: OccasionalClutchClutch that slips or judders, especially when coldThe 1.0 SCe can have a clutch that slips or judders, especially with a cold engine. It is the issue that recurs most in the sources consulted, documented independently on the Sandero II, the Logan II and the Twingo III, without being described as a fault that damages the engine.
- Medium severityFrequency: OccasionalElectronicsJerking, rough idle or warning light from sensors and ignition coilsThe 1.0 SCe can jerk, run unevenly or light up the engine fault warning light because of sensor faults (lambda sensor), ignition coils or injection management. It is a recurring but minority issue in the sources consulted, unrelated to a mechanical problem with the engine block.
- Low severityFrequency: OccasionalLubricationHigher-than-normal oil consumption (especially on the Dacia Sandero II)The Dacia Sandero II with the 1.0 SCe can use more oil than normal, with one documented case of 750 ml every 5,000 km; on the Dacia Logan II and the Renault Twingo III with the same engine this problem is not described in a comparable proportion.
- Low severityFrequency: RareTimingChain-driven timing: no documented pattern of faultsUnlike engines with a timing belt, the 1.0 SCe barely records any mentions of the timing in the sources consulted: 1 case out of 117 combined reviews of the Sandero II, the Logan II and the Twingo III, with no further detail. It is not a fault that we can document as a pattern on this engine.
Buying a 2018 Smart Forfour?
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Frequently asked questions
Is the 2018 Smart Forfour reliable?
The 2018 Smart Forfour was sold with 2 engines that we have documented: the 0.9 TCe and the 1.0 SCe (B4D). The 0.9 TCe has serious faults that affect the cars of that year. The safest option is the 1.0 SCe (B4D) (verdict “With caution”).
Is the 2018 Smart Forfour better than the 2017?
Our score goes from 6.4 in 2017 to 7.8 in 2018. No longer affected by: front left hub carrier with insufficient strength (2017 campaign) (rest of the car) and 12 V battery: a common reason for roadside assistance on 2015 to 2017 Forfours (rest of the car).
What is the best year for the Smart Forfour?
According to our score, the best are 2019 and 2018 (7.8/10). The year with the worst score is 2015 (6.4/10). Each year's score counts only the engines sold that year and the faults that affect those cars.
What faults does the 2018 Smart Forfour have?
The most important ones documented for 2018 cars are: timing chain or tensioner failure (0.9 TCe, critical severity), coolant leak at the thermostat housing (0.9 TCe, high severity), turbocharger wear or failure (0.9 TCe, high severity), clutch that slips or judders, especially when cold (1.0 SCe (B4D), medium severity) and jerking, rough idle or warning light from sensors and ignition coils (1.0 SCe (B4D), medium severity).
Own a 2018 Smart Forfour? Tell us what faults you have had and at how many kilometres. Report your fault.
Sources
Every fact on this page links to its source. If you find an error, let us know.
- Mercedes-Benz M281 engineWikipedia (inglés) · Other source · consulted 27 September 2026
- Smart ForfourWikipedia (inglés) · Other source · consulted 27 September 2026
- Moteur H Renault-NissanWikipedia (francés) · Other source · consulted 27 September 2026 · in French
- Fiabilité des 0.9 TCeFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
- Fiabilité et pannes de la Dacia Sandero 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
- Fiabilité et pannes du Dacia Logan 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
- Fiabilité et pannes de la Renault Twingo 3Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French