Where is the coolant temperature sender located on a 1991 Buick Regal 3.8L engine?

The coolant temperature sender on a 1991 Buick Regal with the 3.8L engine is typically located on the cylinder head, near the thermostat housing. However, there might be *two* senders: one for the gauge and one for the computer (ECM).

To be certain, you'll need to:

1. Consult a repair manual: A Haynes or Chilton manual specific to your year and model Buick Regal will have diagrams showing the exact location. This is the most reliable method.

2. Look at the engine: With the engine cool, carefully examine the cylinder head and thermostat housing area. Look for a sensor with one or two wires connected to it. It's usually a smaller sensor compared to other components in that area.

3. Trace the wires: If you find a sensor, trace the wires. One wire will likely lead to the instrument cluster (gauge sensor), and the other (if present) will lead to the engine control module (ECM).

Remember to let the engine cool completely before attempting to locate the sensor to avoid burns.