Home / Common Problems / Smart (mcc) Forfour

Smart (mcc) Forfour Problems & Known Issues

The most common Smart (mcc) Forfour problems ranked by severity — what to watch for, what it costs to fix, and what happens if you ignore it.

Generations

W454 — First Generation
2004–2006
1.0 Suprex, 1.1 Mitsubishi, 1.3 Mitsubishi, 1.5 DCI, 1.5 Mitsubishi
W453 — Second Generation
2014–2019
0.9 Turbo, 1.0 Naturally Aspirated

Top issues to watch for

The most serious Smart (mcc) Forfour problems ranked by severity. We track 5 known issues — here are the ones you need to know about first.

Major
Emissions system failure (W453)
W4532014–201920k–60k miles
The 0.9L turbocharged and 1.0L naturally aspirated engines in W453 ForFour show exceptionally high MOT failure rates for emissions-related defects. The turbo variant appears particularly affected, likely due to higher combustion temperatures and boost system complexity affecting sensor operation and exhaust gas recirculation.
What happens if ignoredFailed MOT test requiring immediate repair before the vehicle can be driven legally. Typical fixes involve lambda sensor replacement, catalytic converter cleaning or replacement, or exhaust system repairs. Total repair costs range from £200-£800 depending on the specific fault.
Independent garage
£200–£600
Specialist
£250–£700
Main dealer
£400–£800
Parts only
£100–£400
Major
Suspension joint wear (W454)
W4542004–200640k–120k miles
First-generation ForFour models show MOT failure rates nearly 10 times the fleet average for suspension component wear, particularly affecting ball joint dust covers and suspension bushes. The shared platform with Mitsubishi Colt means parts wear patterns are similar. Worn suspension components affect handling safety and will cause MOT failure.
What happens if ignoredMOT failure and compromised handling safety. Worn ball joints can separate causing loss of steering control. Typical repair involves replacement of affected joints, bushes and alignment check. Labour-intensive due to subframe removal requirements.
Independent garage
£300–£600
Specialist
£400–£700
Main dealer
£500–£900
Parts only
£150–£350
Major
Wheel bearing failure (W454)
W4542004–200660k–120k miles
MOT data shows first-generation ForFour models fail for wheel bearing roughness at over 12 times the fleet average. The Mitsubishi-sourced front wheel bearing assemblies appear prone to premature wear, particularly on higher mileage examples. Failed bearings create safety risks and will cause MOT failure.
What happens if ignoredMOT failure and potential wheel collapse if bearing completely fails. Worn bearings affect braking efficiency and steering precision. Replacement requires hub assembly removal and is moderately labour-intensive.
Independent garage
£150–£300
Specialist
£200–£350
Main dealer
£250–£450
Parts only
£80–£180
Minor
Steering rack gaiter deterioration (W454)
W4542004–2006100k–150k miles
MOT data shows W454 ForFour models fail at nearly 13 times the fleet average for steering rack gaiter and ball joint dust cover deterioration. These rubber protective covers prevent dirt and water ingress to steering components. While not immediately dangerous, failed gaiters allow contamination that accelerates wear of expensive steering components.
What happens if ignoredMOT advisory initially, becoming a failure if deterioration is severe. Failed gaiters allow dirt and water to contaminate steering rack internals, leading to expensive rack replacement if left unrepaired. Gaiter replacement is relatively inexpensive preventative maintenance.
Independent garage
£80–£150
Specialist
£100–£180
Main dealer
£120–£220
Parts only
£20–£50

1 more known issues tracked

Including wear items, electrical niggles, and generation-specific problems. Check a specific car to see which issues apply to its age and mileage.

Check a specific car →

MOT failure hotspots

Based on DVSA MOT test data. These are the items where the Smart (mcc) Forfour fails at a significantly higher rate than the average car.

Body panel damage
Bodywork · 80-100k miles
MOT failure rate: 95x the fleet average
Sample: 864 tests
Stop lamp with a multiple light source up to 1/...
Lights & Electrics · 40-60k miles
MOT failure rate: 55x the fleet average
Sample: 214 tests
Emissions failure
Exhaust & Emissions · 40-60k miles
MOT failure rate: 21x the fleet average
Sample: 6,234 tests
Headlight fault
Lights & Electrics · 40-60k miles
MOT failure rate: 19x the fleet average
Sample: 512 tests
Wheel badly distorted or wear between wheel and...
Wheels · 150k+ miles
MOT failure rate: 16x the fleet average
Sample: 114 tests
Any part of the noise suppression system insecure
Exhaust & Emissions · 60-80k miles
MOT failure rate: 16x the fleet average
Sample: 3,096 tests

Buying a Smart (mcc) Forfour?

Check a specific car's service history to see if it's been looked after — franchised dealer records with dates, mileage, and work done.

Check service history

£6.99 · Full refund if no records found

Related

Smart (mcc) Forfour reliability FAQs

What are the most common problems with the Smart (mcc) Forfour?

The Smart (mcc) Forfour has 5 known issues across 2 severity levels. The most common problems relate to Emissions system failure (W453) and Suspension joint wear (W454).

Is the Smart (mcc) Forfour reliable?

The Smart (mcc) Forfour has 0 dangerous and 3 major known issues. No dangerous issues are tracked, which is a positive sign.

How much does it cost to fix Smart (mcc) Forfour problems?

Repair costs range widely. The most significant issue (Emissions system failure (W453)) costs £200–£600 at an independent garage. Minor issues can be under £200. Always get a full inspection before buying.

Which Smart (mcc) Forfour generation is most reliable?

The W454 (2004–2006) has the fewest dangerous issues (0). However, condition and service history matter more than generation — a well-maintained earlier car can be more reliable than a neglected newer one.