P0335 Crankshaft Position Sensor on Smart Fortwo 451 / 453
P0335 flags a crankshaft position (CKP) sensor circuit problem. On a Smart the typical pattern is a no‑start that imitates a bad battery or starter, or a stall when hot that restarts after cooling off. Connector corrosion and a heat‑fatigued sensor are almost always the culprits; actual reluctor ring damage is rare.
Typical Symptoms
- Check engine light with P0335
- Engine cranks but won't start
- Stalls when hot and restarts after cooling
- Tach needle stays at zero while cranking
- Occasional random stall at idle on the 453
- Sometimes paired with P0336 or P0340
What it means
The crankshaft position sensor reads teeth on a reluctor ring spinning with the crankshaft. Without that timing signal, the ECU can't fire spark or fuel at the right moment. P0335 means the ECU lost the signal or saw noise it couldn't interpret. On Smarts the sensor sits very close to the block and cooks over time, so the connector and sensor itself are the cheap first checks.
Likely causes, cheapest first
- Connector corroded or loose at the sensor. Green corrosion, oil saturation or a loose pin are common and free to check.
- Sensor heat‑fatigued. Works cold and fails hot; the most common failure once the connector is clean.
- Wiring harness chafed along its route. Rare but possible where the harness rubs against metal edges.
- Reluctor ring damage on the flywheel. Chipped or rust‑pitted teeth give the ECU bad data; this is the worst case.
DIY check steps
- Locate the sensor on the block (rear of the 451, tighter access on the 453) and unplug the connector. Inspect for corrosion, oil or loose pins and push it back until it clicks.
- If the problem is intermittent, do a wiggle test – with the engine running, gently move the connector and harness. If the engine cuts out, you've found a bad pin or wire.
- Replace the sensor. On the 451 it's one bolt and one plug and takes about 15 minutes; on the 453 allow an hour.
- Clear the code and drive normally. If it stays gone after a connector clean and sensor swap, you're done.
When to call a shop
If a clean connector and new sensor don't stop P0335, a shop visit with MB Star or equivalent is next. A scan tool reading live crank signal data can distinguish between wiring noise and missing reluctor teeth. Flywheel replacement requires dropping the transmission and is not DIY for most owners.
Related parts & typical prices
| Part | Typical price | Search |
|---|---|---|
| Crankshaft position sensor (451) | $30-120 | Search Google |
| Crankshaft position sensor (453) | $50-180 | Search Google |
| Sensor connector / pigtail repair kit | $10-25 | Search Google |
Prices are rough community-reported ranges, not quotes. Aftermarket vs. genuine Mercedes parts swing the spread; call a Smart-experienced shop for an actual quote.
Manual references
- Service manual on Manualslib — external mirror (we don't host this specific document).
- Browse Smart manuals on smartcarmanuals.com — pick your chassis code section on the home page if a specific manual isn't listed above.
Community references
- Evilution: OBD-II error code reference (P0335 listing)
- Evilution: 453 wastegate fault thread (cross-reference for P0335 cluster)
- FQ101: OBD code lookup
Stuck on this one?
SmartDiag-AI runs through the cheap-first checks with you, weighted to community-known patterns for your exact model. The link below pre-fills the code and model.