Fuse Box Layout on Smart Fortwo 450, 451, and 453
Service interval: Inspect when a circuit drops out — not on a schedule
Tools you'll need
- Plastic fuse pull tool (or fingers / needle-nose pliers in a pinch)
- Small flat screwdriver to release some panel clips
- Phone flashlight
What this is and why it matters
A blown fuse is the cheapest fix on the car, but only if you can find the right one. Smart moved the fuse box around across the three Fortwo generations, and on the 453 they split it into two separate modules with very different access. Knowing which box you're opening — and which fuses inside it are owner-territory versus shop-territory — saves a lot of dash teardown for nothing.
This page is a reference. Use it when something on the car has gone dead and you suspect a fuse: fuel pump silent on key-on, a single headlight out, dash accessory dead. The diagram printed inside the cover (and in the workshop manual) tells you which fuse drives which circuit. Your job is just to get to the right cover.
What you'll need
Almost nothing. A plastic fuse puller helps, but fingers or thin needle-nose pliers do the same job. A spare assortment of mini blade fuses in common ratings (5, 7.5, 10, 15, 20, 25, 30A) lives well in the glovebox.
What you do not want: pliers that scratch the fuse, a fuse of the wrong rating "to get home," or a paperclip jumper across blown contacts. A 30A fuse where a 10A belongs is how harnesses melt.
How to find the right fuse
This is a reference page, not a procedure. The flow is the same on all three generations:
- Identify the symptom. Fuel pump silent at key-on, single headlight out, radio dead, power outlet not working — write down what dropped out so you know what circuit you're chasing.
- Open the relevant fuse box for your generation (locations below). Pull the cover off — most are friction-fit plastic, no fasteners.
- Use the diagram to find the fuse for that circuit. The diagram is printed on the inside of the cover on most cars. If the cover label is missing or rubbed off, the workshop manual has the same chart. Pull the suspect fuse, hold it to the light, and look at the metal strip. Broken strip = blown. Replace with the same amp rating only.
Smart Fortwo 450 (1998-2007)
The 450's main fuse box sits under the cockpit on the left-hand side, low on the driver's footwell area. The Workshop Repair Manual covers it in the Communication and Breakdown supplement. The cover pulls downward off plastic clips — no tools needed for most years. Inside you'll see a typical 12-position panel covering ECU power, fuel pump, lighting, wipers, and accessories.
The 450 also has a relay block colocated with the fuse panel. The fuel pump relay is the one most owners go after — it's a common no-start cause on this generation.
Smart Fortwo 451 (2007-2015)
On the 451, the main owner-accessible fuse box sits behind a panel in the driver's footwell, with a secondary block behind or near the glovebox depending on year and market. The exact panel varies between coupe, cabrio, and electric drive. Pull the kick panel by hand or with a small flat screwdriver to release the clips. The diagram is on the cover or in the manual.
The 451 introduced more centralized electrical control via the SAM (see the SAM module overview), and a few circuits that look like fuses on older cars are actually relay logic inside the SAM. If the fuse for a circuit looks fine and the circuit is still dead, the SAM is the next suspect — not another fuse.
Smart Fortwo 453 (2014-present)
The 453 splits its fuse and relay layout into two modules:
- F1, the engine compartment fuse and relay module. Lives under the rear hood, near the engine. Most owner-replaceable fuses are here — main power feeds, charging, fuel pump, fans, headlights. Lift the rear hood, pop the F1 cover, work from the diagram.
- F2, the vehicle interior fuse and relay module. Lives behind the dash trim on the driver's side. This is shop territory for most owners — the relays inside (like F2K5, the starter relay covered in the related fault code page) are not pull-and-swap parts. They live inside the module and are managed by the SAM.
For a 453, if the symptom maps to an interior accessory or to starter logic, the F2 module is where the fault sits, but you don't open it casually. F1 is the one you actually work in.
Common gotchas
Pulling a fuse that looks blown and finding the strip intact means the circuit is broken somewhere else — relay, wire, or the load itself. The fuse is a witness, not always the cause.
Replacing a blown fuse and watching it pop again immediately means there's a short downstream. Stop. Don't keep feeding fuses into a shorted circuit. Find the short first.
Fuse ratings matter. A 15A circuit that keeps blowing 15s is asking why; the answer is not a 20A. Up-rating a fuse turns a controlled failure into a melted harness.
Mixed up amp colors: standard mini blade fuse colors are roughly tan/5A, brown/7.5A, red/10A, blue/15A, yellow/20A, clear or natural/25A, green/30A. Useful for a fast eyeball check, but always confirm the printed number on the fuse body.
When to skip DIY
The 453's F2 module is shop work. If you've narrowed a 453 fault down to F2, that's diagnosis territory for someone with Star Diagnosis or equivalent — the module pairs to the SAM and to other modules on the bus, and a swap requires a coding step.
A circuit that keeps blowing fuses no matter what you do means a short to ground somewhere in the harness. That's a tracing job that gets expensive fast on the driveway. A shop with proper diagnostic gear is the right call.
If the fuse box itself shows heat damage — melted plastic around a slot, discoloration on the bus bars — don't keep using it. Heated fuse boxes are how cars catch fire. Replace the panel or have a shop look at it.
Parts & typical prices
| Part | Typical price | Search |
|---|---|---|
| Mini blade fuses (assorted amp ratings) | $5-15 for a kit | Search Google |
| Fuse pull tool | $2-5 | Search Google |
Prices are rough community-reported ranges, not quotes. Aftermarket vs. genuine Mercedes parts swing the spread.
Manual references
- Browse Smart workshop manuals on smartcarmanuals.com — model-specific reference manuals on the home page; pick your chassis code section for torque specs and detailed procedures.
How-to videos
Related fault codes
- B152014 F2K5 Starter Relay Fault on Smart Fortwo 453
- C1000 ABS / ESP Control Module Fault on Smart Fortwo 451 and 453