At a Glance
Smart has 65 identified common problems across 5 models, with the Roadster being the most affected model and electrical the most common problem category. Based on 1.3M MOT tests from DVSA data.
Problems are patterns in the DVSA data that occur significantly more often on a specific model than the UK average — confirmed at 99% statistical confidence. Read how we identify common car problems →
Below: per-model breakdowns of Smart common problems, MOT failure rates by category, pass-rate data, and repair patterns drawn from 1.3M DVSA MOT tests across 20 years. Click any model to see generation-specific issues, mileage-banded fault patterns, and the most common MOT failures recorded by UK testers.
MOT Tests & Failures by Model
Top Smart models by MOT tests, failures, and identified problems from DVSA data
Hover over each bar for a full breakdown. Tap any bar to view that model's problems.
Showing total MOT tests, failures, and known problems per make. Hover over each bar for a full breakdown.
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Smart Common Problems by Model
Select a model to see problems by generation
Most Common Smart MOT Failures
Every reason Smart vehicles fail their MOT, ranked by frequency. Select an individual year to see only that year’s failures, or stay on ‘All time’ for the combined picture across our 20 years of DVSA data. Scroll inside the table for the full list.
| # | Failure | % of failures |
|---|---|---|
| 1 | Wiper blades deteriorated | 8.78% |
| 2 | Tyre tread depth below limit | 7.83% |
| 3 | Windscreen washer not working | 6.55% |
| 4 | Suspension joint or bush worn | 6.50% |
| 5 | Stop lamp not working | 6.10% |
| 6 | Tyre condition | 5.92% |
| 7 | Brake performance below minimum | 5.13% |
| 8 | Number plate lamp not working | 4.70% |
| 9 | Coil spring broken or corroded | 4.56% |
| 10 | Headlamp aim defect | 3.45% |
| 11 | Brake pads or linings worn | 3.00% |
| 12 | Position lamp not working | 2.67% |
| 13 | Front lamp not working | 2.52% |
| 14 | Catalytic converter efficiency low | 2.13% |
| 15 | Spark ignition emissions above threshold | 2.07% |
| 16 | Brake disc or drum worn | 1.97% |
| 17 | Headlamp fault | 1.94% |
| 18 | Brake hydraulic component worn | 1.70% |
| 19 | Exhaust system fault | 1.67% |
| 20 | Rigid brake pipe corroded or damaged | 1.44% |
| 21 | Track rod end worn | 1.28% |
| 22 | Indicator fault | 1.24% |
| 23 | Shock absorber worn or leaking | 1.23% |
| 24 | Ball joint dust cover split | 1.04% |
| 25 | Parking brake performance below minimum | 1.00% |
| 26 | Rear lamp not working | 0.93% |
| 27 | Horn not working | 0.93% |
| 28 | Windscreen damage affecting view | 0.93% |
| 29 | Airbag warning light on | 0.83% |
| 30 | ABS fault | 0.69% |
| 31 | Front suspension joint worn | 0.69% |
| 32 | Fog lamp not working | 0.57% |
| 33 | Wheel bearing worn | 0.49% |
| 34 | Mirror damaged or missing | 0.42% |
| 35 | Front suspension fault | 0.40% |
| 36 | Compression ignition emissions above threshold | 0.40% |
| 37 | Rear suspension fault | 0.40% |
| 38 | Flexible brake hose damaged | 0.37% |
| 39 | Driveshaft fault | 0.36% |
| 40 | MacPherson strut worn | 0.32% |
| 41 | Seat belt condition | 0.26% |
| 42 | Tyre size or type not matched | 0.23% |
| 43 | Rear fog lamp not working | 0.23% |
| 44 | Engine mounting worn or broken | 0.21% |
| 45 | Tyre valve stem damaged | 0.21% |
| 46 | Suspension arm worn or corroded | 0.19% |
| 47 | Parking brake condition | 0.18% |
| 48 | Battery loose or leaking | 0.16% |
| 49 | Engine oil leak | 0.16% |
| 50 | Body corrosion or damage | 0.15% |
| 51 | Tyre pressure monitoring system fault | 0.14% |
| 52 | Brake lever fault | 0.13% |
| 53 | Brake pedal fault | 0.12% |
| 54 | Suspension mounting corroded | 0.12% |
| 55 | Steering rack fault | 0.11% |
| 56 | Brake pedal movement restricted | 0.10% |
| 57 | Bumper damaged or insecure | 0.10% |
| 58 | Front passenger door fault | 0.10% |
| 59 | Electronic stability control fault | 0.09% |
| 60 | Electrical switch fault | 0.08% |
| 61 | Headlamp levelling device fault | 0.08% |
| 62 | Driver door fault | 0.08% |
| 63 | Bonnet catch or hinge fault | 0.07% |
| 64 | Suspension linkage fault | 0.07% |
| 65 | Handbrake lever fault | 0.07% |
| 66 | Fuel cap damaged or missing | 0.07% |
| 67 | Rear reflector damaged or missing | 0.06% |
| 68 | Electrical wiring fault | 0.06% |
| 69 | Steering operation fault | 0.06% |
| 70 | Brake caliper fault | 0.06% |
| 71 | Undertray damaged or missing | 0.05% |
| 72 | Reversing lamp not working | 0.05% |
| 73 | Driver airbag fault | 0.05% |
| 74 | Steering lock fault | 0.05% |
| 75 | Brake fluid level low or contaminated | 0.04% |
| 76 | Dashboard warning lamp fault | 0.04% |
| 77 | Brake fluid leak | 0.04% |
| 78 | Handbrake cable fault | 0.04% |
| 79 | Brake cable, rod, lever or linkage fault | 0.03% |
| 80 | Steering column fault | 0.03% |
| 81 | Body security fault | 0.03% |
| 82 | Hydraulic brake cylinder fault | 0.03% |
| 83 | Steering free play excessive | 0.03% |
| 84 | Chassis condition | 0.03% |
| 85 | Brake fluid warning light on | 0.02% |
| 86 | Anti-roll bar worn or corroded | 0.02% |
| 87 | Speedometer fault | 0.02% |
| 88 | Vehicle structure corrosion | 0.02% |
| 89 | Steering wheel damaged or insecure | 0.02% |
| 90 | Steering arm worn | 0.02% |
| 91 | Boot lid damaged or insecure | 0.02% |
| 92 | Fuel pipe corroded or damaged | 0.02% |
| 93 | Universal joint worn | 0.02% |
| 94 | Steering coupling worn | 0.01% |
| 95 | Driver seat fault | 0.01% |
| 96 | Steering damper fault | 0.01% |
| 97 | Rear fog lamp warning light fault | 0.01% |
| 98 | Brake wheel cylinder fault | 0.01% |
| 99 | Dip switch fault | 0.01% |
| 100 | Tie bar or rod worn or corroded | 0.01% |
| 101 | Drag link end worn | 0.01% |
| 102 | Subframe corrosion or damage | 0.01% |
| 103 | Fuel hose damaged or leaking | <0.01% |
| 104 | King pin or swivel pin worn | <0.01% |
| 105 | Electric power steering fault | <0.01% |
| 106 | Indicator warning light fault | <0.01% |
| 107 | Brake fluid reservoir fault | <0.01% |
| 108 | Main beam warning light fault | <0.01% |
| 109 | Exhaust emissions above threshold (non-catalyst) | <0.01% |
| 110 | Bonded suspension condition | <0.01% |
| 111 | Exhaust leak | <0.01% |
| 112 | Mirror or camera fault | <0.01% |
| 113 | Passenger airbag fault | <0.01% |
| 114 | Passenger seat fault | <0.01% |
| 115 | Propshaft fault | <0.01% |
| 116 | Brake servo fault | <0.01% |
| 117 | Suspension unit fault | <0.01% |
| 118 | Brake air or vacuum system fault | <0.01% |
| 119 | Radius arm worn or corroded | <0.01% |
| 120 | Tailgate damaged or insecure | <0.01% |
| 121 | Window damaged or won't operate | <0.01% |
| 122 | Electronic braking system fault | <0.01% |
| 123 | Brake master cylinder fault | <0.01% |
| 124 | Transmission drive belt fault | <0.01% |
| 125 | Fuel tank corroded or leaking | <0.01% |
| 126 | Access panel damaged or insecure | <0.01% |
| 127 | Suspension rod worn or corroded | <0.01% |
| 128 | Additional braking device fault | <0.01% |
| 129 | Trailing arm worn or corroded | <0.01% |
| 130 | Transmission oil leak | <0.01% |
| 131 | Panhard rod worn or corroded | <0.01% |
| 132 | Front fog lamp not working | <0.01% |
| 133 | Towbar fault | <0.01% |
| 134 | Daytime running lamp not working | <0.01% |
| 135 | Brake valve fault | <0.01% |
| 136 | Hazard warning light fault | <0.01% |
| 137 | Hydraulic fluid leak | <0.01% |
| 138 | Subframe mounting corroded | <0.01% |
| 139 | Seat belt anchorage fault | <0.01% |
| 140 | Suspension retaining or locking device fault | <0.01% |
| 141 | Axle corroded or damaged | <0.01% |
| 142 | Brake back plate corroded or damaged | <0.01% |
| 143 | Brake pressure or vacuum buildup insufficient | <0.01% |
| 144 | Suspension linkage attachment bracket or mounting corroded | <0.01% |
| 145 | Torque or reaction arm worn | <0.01% |
| 146 | Full power hydraulic brake fault | <0.01% |
| 147 | Outline marker lamp not working | <0.01% |
| 148 | Power steering ram fault | <0.01% |
| 149 | Leaf spring broken or corroded | <0.01% |
| 150 | Body strengthening plate corroded | <0.01% |
| 151 | Seat belt pre-tensioner fault | <0.01% |
| 152 | Steering drive system fault | <0.01% |
| 153 | Steering shaft fault | <0.01% |
| 154 | Torsion bar worn or corroded | <0.01% |
| 155 | Wheel hub fault | <0.01% |
| 156 | Stub axle worn | <0.01% |
| 157 | Axle beam corroded or cracked | <0.01% |
| 158 | Loading door damaged or insecure | <0.01% |
| 159 | Reversing lamp switch fault | <0.01% |
| 160 | Semaphore indicator fault | <0.01% |
| 161 | Spring mounting corroded | <0.01% |
| 162 | Electronic parking brake fault | <0.01% |
| 163 | Exhaust heat shield or sound insulation damaged | <0.01% |
| 164 | Passenger compartment corrosion | <0.01% |
| 165 | Seat belt or padding damaged | <0.01% |
| 166 | Steering box fault | <0.01% |
| 167 | Steering lock stop fault | <0.01% |
| 168 | Vehicle floor corroded | <0.01% |
| 169 | Brake slack adjuster fault | <0.01% |
| 170 | Headlamp washer not working | <0.01% |
| 171 | Securing bolts missing or insecure | <0.01% |
| 172 | Steering intermediate drop arm worn | <0.01% |
| 173 | Brake master cylinder or servo mounting fault | <0.01% |
| 174 | Brake relay lever fault | <0.01% |
| 175 | Halfshaft fault | <0.01% |
| 176 | Power steering pipe or hose leaking | <0.01% |
| 177 | Brake clevis joint worn | <0.01% |
| 178 | Brake pedal linkage fault | <0.01% |
| 179 | Hand-operated brake valve condition | <0.01% |
| 180 | Hinged tailboard damaged or insecure | <0.01% |
| 181 | Load sensing valve fault | <0.01% |
| 182 | Passenger hand grip fault | <0.01% |
| 183 | Power steering pump fault | <0.01% |
| 184 | Seat belt load limiter fault | <0.01% |
| 185 | Spare wheel fault | <0.01% |
| 186 | Steering head bearings worn | <0.01% |
| 187 | Speed limiter fault | <0.01% |
Showing all 187 reasons — scroll inside the table for the full list.
Smart MOT Failures by Category
Total MOT failure occurrences for Smart, grouped by category. Same data as the failures table above — just sliced by category instead of fault title. Hover a slice for the top failures in each category.
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Frequently Asked Questions
What are the most common Smart problems?
Based on analysis of 1.3M Smart MOT tests from DVSA data, Smart has 65 identified common problems across 5 models. The Smart Roadster has the most recorded problems. Electrical issues are the most common category.
Which Smart model has the most problems?
By total identified common problems, the Smart Roadster has the highest count with 32 problems. This is partly because it is one of the more popular Smart models on UK roads. See the models grid for a full breakdown.
How is this data calculated?
We analyse anonymised DVSA MOT test records under the Open Government Licence. An issue is classified as a "Common Problem" when it occurs significantly more often on a specific model than the UK average, confirmed at 99% statistical confidence. Read the full methodology page for details.
Can I report a problem with my Smart?
Yes — use the "Tell Us About Your Problem" form on this page. Your report helps other Smart owners spot problems early. We review all submissions before they are published.
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