Where is the temperature sending unit on a 04 Chevy 3.8Liter six cylinder engine?

On a 2004 Chevy 3.8L V6, the temperature sending unit (for the gauge in the instrument cluster) is typically located on the cylinder head, near the thermostat housing. It's a one-wire sensor, often a smaller sensor compared to other sensors in that area.

However, there's no single definitive location that works across all 2004 Chevy 3.8L V6 vehicles. Slight variations in the engine bay layout exist depending on the exact model and trim level.

To locate it accurately:

1. Consult a repair manual: A Chilton's or Haynes repair manual specific to your year, make, and model will have a diagram showing the exact location of all sensors. This is the most reliable method.

2. Use a wiring diagram: If you have access to a wiring diagram for your vehicle's electrical system, trace the wire from the temperature gauge to its source. This will lead you directly to the sender.

3. Visual Inspection: With the engine cool, carefully examine the area around the thermostat housing and cylinder head. Look for a small, single-wire sensor that's likely threaded into the engine block or cylinder head.

Caution: Always allow the engine to cool completely before attempting to locate or work on any engine components. Be aware of hot coolant and other engine components.