Smart ForFour 454 — Problems & Common Faults
Weaknesses, engine ratings and buying advice
The smart ForFour 454 (2004–2006) is the odd one out in early smart history: a four-door compact, closely related to the Mitsubishi Colt and built in the shared plant in the Netherlands (NedCar). With it, smart left its uncompromising two-seater concept – the ForFour is more conventional, larger (3.75 m) and more family-friendly, but lost the brand's compact unique selling point. It is powered by Mitsubishi petrol engines: 1.1 (3A91), 1.3 and 1.5 (4A90/4A91) with 55 to 80 kW, plus the 1.5 CDI diesel. Unlike the ForTwo, a conventional manual gearbox was available here alongside the automated one, which avoids the notorious jerk. The mechanicals are considered solid and typically Mitsubishi-durable; weak points are mostly age-related: rust on the wheel arches and sills, worn suspension bushes, timing-chain issues on the smaller engines and the usual electrical niggles. Because of commercial failure and a short production run, few were sold, so it is rare on the market today – but it fortunately shares parts with the widespread Colt. The automated gearbox (softtouch/softip) shows the same weaknesses here as in the ForTwo; the manual variants are more relaxed in daily use and usually the better choice. The 1.5 CDI diesel is economical but needs well-maintained injectors and an intact EGR system. Market status 2026: cheap (roughly 1,500–4,000 euros) but hard to find, especially in good condition – the low numbers make a targeted search a test of patience. One advantage: mechanical parts are readily and cheaply available via the Mitsubishi Colt, only smart-specific body and interior parts can be scarce. For buyers wanting a small, economical four-door with smart looks and Mitsubishi reliability, it is an underrated choice – watch for rust, a well-kept suspension and full history. As a practical, affordable city and short-trip car with four seats, it offers good value for money.
177 PS
ForFour · Benzin
Pocket rocket with four seats
Legendary!95 PS
1.3L Benzin
4 weaknesses
Good Choice109–177 PS
1.5L Benzin
4 weaknesses
Stay Away!Generations
Engine Overview
The Smart ForFour 454 is available with 6 engine variants — from 64 to 177 hp.
The Mitsubishi-based three-cylinder diesel is tuned for low consumption and delivers usable torque for its size, but stays acoustically rough and gritty. As a compression-ignition unit it needs long periods at operating temperature and suffers under predominantly short-trip use: the diesel particulate filter clogs because regeneration fails to occur, and the injectors tend towards uneven metering with power loss and rough running. Before buying, read out the DPF soot load, check injector return quantities and mind the history. An example run mostly on long distances with good maintenance is economical and durable.
No known weaknesses documented.
The Mitsubishi-based three-cylinder diesel is tuned for low consumption and delivers usable torque for its size, but stays acoustically rough and gritty. As a compression-ignition unit it needs long periods at operating temperature and suffers under predominantly short-trip use: the diesel particulate filter clogs because regeneration fails to occur, and the injectors tend towards uneven metering with power loss and rough running. Before buying, read out the DPF soot load, check injector return quantities and mind the history. An example run mostly on long distances with good maintenance is economical and durable.
No known weaknesses documented.
A solid Mitsubishi three-cylinder using a timing chain rather than a belt, which keeps maintenance costs low. Its output is entirely adequate for the light small car in town and country driving, though it naturally lacks reserves on the motorway. The engine is regarded as durable and undemanding, with no known critical design flaws. Typical age-related items are hardened engine mounts, a leaking valve-cover gasket and sluggish oxygen sensors. Before buying, check for a steady idle and complete service history, then the unit runs trouble-free well beyond 200,000 kilometres.
- !! Timing chain stretched from 120,000 km
The timing chain of the 3A91 can stretch, especially when oil changes are neglected. One forum case was documented at just 53,000 km. Repair costs approx. €1,400.
Symptoms: Metallic rattling on cold start, engine running rough as if on two cylinders, engine warning light, engine cutting out while driving - !! Valve clearance drifts out of spec from 100,000 km
The 3A91 Mitsubishi engine requires a valve clearance check at 100,000 km and adjustment if necessary. If this is missed, engine running deteriorates and fuel consumption rises.
Symptoms: Ticking noises from the valvetrain, rough idle, increased fuel consumption, poorer throttle response - !! Clutch actuator and premature clutch wear from 100,000 km
The automated transmission of the 451 wears the clutch significantly faster than a manual gearbox. By 100,000 km the second clutch is often due.
Symptoms: Jerking when pulling away, delayed clutch engagement, shifting problems, MHD function unreliable
+ 1 more engine weaknesses + vehicle weaknesses
A solid Mitsubishi three-cylinder using a timing chain rather than a belt, which keeps maintenance costs low. Its output is entirely adequate for the light small car in town and country driving, though it naturally lacks reserves on the motorway. The engine is regarded as durable and undemanding, with no known critical design flaws. Typical age-related items are hardened engine mounts, a leaking valve-cover gasket and sluggish oxygen sensors. Before buying, check for a steady idle and complete service history, then the unit runs trouble-free well beyond 200,000 kilometres.
- !! Timing chain stretched from 120,000 km
The timing chain of the 3A91 can stretch, especially when oil changes are neglected. One forum case was documented at just 53,000 km. Repair costs approx. €1,400.
Symptoms: Metallic rattling on cold start, engine running rough as if on two cylinders, engine warning light, engine cutting out while driving - !! Valve clearance drifts out of spec from 100,000 km
The 3A91 Mitsubishi engine requires a valve clearance check at 100,000 km and adjustment if necessary. If this is missed, engine running deteriorates and fuel consumption rises.
Symptoms: Ticking noises from the valvetrain, rough idle, increased fuel consumption, poorer throttle response - !! Clutch actuator and premature clutch wear from 100,000 km
The automated transmission of the 451 wears the clutch significantly faster than a manual gearbox. By 100,000 km the second clutch is often due.
Symptoms: Jerking when pulling away, delayed clutch engagement, shifting problems, MHD function unreliable
+ 1 more engine weaknesses + vehicle weaknesses
The Mitsubishi four-cylinder is considered the most mature and balanced drivetrain option in its series. It runs smoother than the three-cylinders, offers noticeably more pull and still keeps consumption in check. The timing chain is designed for low maintenance and no serious weaknesses are documented. Over the years the usual age points appear: engine mounts, thermostat, spark plugs and occasionally leaking camshaft adjusters. Anyone who finds a well-kept example with a clean service history gets a lastingly reliable and cheap-to-run drivetrain.
- !! Timing chain stretches with neglected oil changes from 95,000 km
The timing chain of the three-cylinder can rattle from 80,000 km with poor oil maintenance. One forum report shows rattling at 95,000 km after 50–60 k km on the same oil. Rare with regular servicing.
Symptoms: Rattling on cold start, metallic clattering from the engine bay, engine warning light with advanced wear - ! Sump gasket leaking — bonded sheet-metal sump from 50,000 km
The sump is made of thin sheet metal and only sealed with sealant compound. From around 40,000 km the seal can start leaking. Oil collects underneath and drips when parked.
Symptoms: Oil patches under the vehicle, oil-coated sump, oil film on the exhaust, dropping oil level - ! Plastic oil filter cap cracks from 40,000 km
The threaded oil filter cap is made of plastic and can develop hairline cracks if over-torqued. Massive oil loss, including oil smeared across the exhaust and rear bumper on the motorway.
Symptoms: Severe oil loss, oil film on exhaust and rear bumper, oil smell, rapidly dropping oil level
+ 1 more engine weaknesses + vehicle weaknesses
The Mitsubishi 1.5-litre four-cylinder comes as a naturally aspirated unit of around 80 kW and as a turbocharged Brabus version of up to 130 kW. The NA variant is uncomplicated, smooth-running and durable, while the turbo version delivers considerably more temperament but stresses the clutch, driveshafts and entire drivetrain noticeably harder. Watch the timing chain and intact engine mounts, and on the turbo also boost pressure and turbocharger condition. A well-kept NA is the stress-free choice, while the Brabus variant demands regular clutch and oil checks.
- !! Wastegate actuator faulty — moisture destroys crown gear from 40,000 km
Moisture enters the plastic housing of the electronic wastegate actuator. Green corrosion on the contacts and broken teeth on the crown gear prevent the valve from closing — no boost pressure.
Symptoms: Yellow engine warning light, no boost pressure, severe power loss, limp mode, sometimes limited to 30 km/h - !! Turbocharger total failure at just 20,000 km from 30,000 km
Some turbochargers fail completely at very low mileage. Workshop diagnoses a faulty turbo; official replacement costs around €2,500 at a Smart dealer.
Symptoms: No throttle response, complete power loss, engine warning light, strong whistling/whining from the turbo area - !! Twinamic dual clutch wears — harsh shifting and judder from 80,000 km
The 6-speed dual-clutch gearbox (Twinamic) shifts harshly and judders on engagement. Crawling in 2nd gear is particularly hard on the clutch as it slips continuously.
Symptoms: Harsh shifting, juddering on pull-away, vibrations at low speeds, clutch smell in stop-and-go traffic
+ 1 more engine weaknesses + vehicle weaknesses
The Mitsubishi 1.5-litre four-cylinder comes as a naturally aspirated unit of around 80 kW and as a turbocharged Brabus version of up to 130 kW. The NA variant is uncomplicated, smooth-running and durable, while the turbo version delivers considerably more temperament but stresses the clutch, driveshafts and entire drivetrain noticeably harder. Watch the timing chain and intact engine mounts, and on the turbo also boost pressure and turbocharger condition. A well-kept NA is the stress-free choice, while the Brabus variant demands regular clutch and oil checks.
- !! Wastegate actuator faulty — moisture destroys crown gear from 40,000 km
Moisture enters the plastic housing of the electronic wastegate actuator. Green corrosion on the contacts and broken teeth on the crown gear prevent the valve from closing — no boost pressure.
Symptoms: Yellow engine warning light, no boost pressure, severe power loss, limp mode, sometimes limited to 30 km/h - !! Turbocharger total failure at just 20,000 km from 30,000 km
Some turbochargers fail completely at very low mileage. Workshop diagnoses a faulty turbo; official replacement costs around €2,500 at a Smart dealer.
Symptoms: No throttle response, complete power loss, engine warning light, strong whistling/whining from the turbo area - !! Twinamic dual clutch wears — harsh shifting and judder from 80,000 km
The 6-speed dual-clutch gearbox (Twinamic) shifts harshly and judders on engagement. Crawling in 2nd gear is particularly hard on the clutch as it slips continuously.
Symptoms: Harsh shifting, juddering on pull-away, vibrations at low speeds, clutch smell in stop-and-go traffic
+ 1 more engine weaknesses + vehicle weaknesses
Vehicle Weaknesses
| Weakness | Cost | |
|---|---|---|
| Sills and Wheel Arches Rust The sills and wheel arch edges of the ForFour 454 are regularly affected by rust on older vehicles, as stone chips and moisture attack quickly. Frequent city use and lack of underbody maintenance accelerate the problem. Symptoms: Rust bubbles on sills and wheel arch edges, visible rust-through, paint flaking from 90,000 km | Medium | |
| Exhaust System Corrodes The ForFour 454 exhaust system rusts primarily at the rear silencer due to typical short-trip city use. Condensation water collects in the silencer and corrodes the steel from the inside. A complete replacement can be due before 80,000 km. Symptoms: Visible rust on the rear silencer, holes in the silencer, increased noise, rattling from 70,000 km | Low |
Test Reports
ADAC Gebrauchtwagen-Test Smart ForFour 454
The first Smart ForFour 454 is overall unremarkable according to ADAC — as the sister model of the Mitsubishi Colt it shares its solid basic construction. In the breakdown statistics only the battery stands out as a notable weak point.
2021-06Alternatives
Smart ForFour 453
Nachfolger (2014–2022)
Mitsubishi Colt Z30
Supermini (2004–2012)
Renault Modus I
Supermini (2004–2012)
Citroën C2 I
Supermini (2003–2010)
Citroën C3 Pluriel I
Supermini (2003–2010)
Fiat Panda 169
Supermini (2003–2012)
Lancia Ypsilon 843
Supermini (2003–2011)
Explore more
Known Problems and Issues +
A total of 22 weaknesses have been documented for the Smart ForFour 454 (2004–2006) — 12 engine-related and 10 vehicle-related. One problem engine: 4A91 (1.5L). Typical issues affect Rust, Suspension, Electronics, Steering. Considered reliable: 4A90 (1.3L).
ForFour (3A91, 2004–2006) — Be Careful: Timing chain stretched, Valve clearance drifts out of spec, Clutch actuator and premature clutch wear. Power: 64 PS.
ForFour (3A91, 2004–2006) — Be Careful: Timing chain stretched, Valve clearance drifts out of spec, Clutch actuator and premature clutch wear. Power: 75 PS.
ForFour (4A91, 2004–2006) — Stay Away!: Wastegate actuator faulty — moisture destroys crown gear, Turbocharger total failure at just 20,000 km, Twinamic dual clutch wears — harsh shifting and judder. Power: 109 PS.
ForFour (4A91, 2005–2006) — Stay Away!: Wastegate actuator faulty — moisture destroys crown gear, Turbocharger total failure at just 20,000 km, Twinamic dual clutch wears — harsh shifting and judder. Power: 177 PS.
What to watch out for with the Smart ForFour? See the detailed listing of all engine and vehicle weaknesses in the sections above.
Frequently Asked Questions
What problems and weaknesses does the Smart ForFour 454 have? +
What should I look for when buying a used Smart ForFour 454? +
Which engine is recommended? +
Which Smart ForFour 454 engine is the most reliable? +
Which Smart ForFour 454 engine is the most fun? +
Is the Smart ForFour 454 worth buying used? +
What horsepower variants are available for the Smart ForFour 454? +
Last updated: February 2026 · All information without guarantee