Chevrolet Cobalt Turn Signal Bulb Size

Chevrolet Cobalt front and rear turn signal bulbs utilize 3457NA and 3357NA sizes for forward applications, with 3157 bulb size specified for rear positions. The replacement chart covers 2005 through 2010 model years with corresponding bulb size specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Front Turn Signal

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2010	3457NA	PY27/7W	Check Price
2007-2009	3357NA	3357NA	Check Price
2005-2006	3457NA	PY27/7W	Check Price

Rear Turn Signal

Years	US Type	EU Type	Shop
2005-2010	3157	P27/7W	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament wedge bulb (T25), natural amber glass. 12V, 27W/7W.	3457NA	Check Price
ANSI standard (US & Canada). Single-filament wedge bulb (T25), natural amber glass. 12V, 27W.	3357NA	Check Price
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157	Check Price

Other Locations

Additional Notes

The front turn signal position on the Chevrolet Cobalt uses two distinct bulb types across its production run: the 3457NA for 2005-2006 and 2010, and the 3357NA for 2007-2009.
The rear turn signal position uses the 3157 bulb across all model years covered by these specifications, from 2005-2010.
The 3457NA and 3357NA bulbs both follow the ANSI standard applicable in the United States and Canada, and both are housed in a T25 wedge form factor with natural amber glass.
Natural amber glass in the 3457NA and 3357NA bulbs produces an amber-colored output without relying on a colored lens, which is a characteristic of the NA (Natural Amber) designation in the ANSI bulb naming system.
The 3457NA is a dual-filament bulb rated at 12V with a 27W high filament and a 7W low filament, allowing it to serve both a bright turn signal function and a dimmer parking or running light function from a single bulb.
The 3357NA is a single-filament bulb rated at 12V and 27W, meaning it is dedicated solely to the turn signal function and does not support a secondary low-power mode.
Despite the 3357NA and 3457NA sharing the same T25 wedge base and physical housing, their filament configurations differ, and substituting one for the other in the front turn signal socket would result in incorrect electrical behavior for the affected model years.
The 3157 rear turn signal bulb is also a dual-filament T25 wedge type rated at 12V, 27W/7W, making its wattage output identical to the 3457NA used at the front, though the 3157 lacks the natural amber glass coating.
The shared T25 wedge base across all three bulb types in these specifications means the physical socket is consistent throughout the vehicle, while the electrical and optical differences between part numbers remain the determining factor for correct fitment.
The front turn signal specification change between the 2006 and 2007 Chevrolet Cobalt, from the dual-filament 3457NA to the single-filament 3357NA, reflects a difference in circuit design between those model years that affects which replacement bulb is electrically appropriate.