Temperature Gauge and Sending Unit Quick-Check

A quick, easy test will determine whether the coolant temperature gauge is correctly representing engine temperature.

If the temperature gauge needle remains at its rest position even though the engine is fully warmed, test the gauge as follows. With the ignition on and the engine not running, disconnect the gauge wire (yellow with red stripe) from the sending unit in the coolant outlet on the cylinder head. On 16-valve engines, the sending unit is on the driver's-side end of the cylinder head. Ground the wire. This simulates a high engine temperature signal to the gauge. If the gauge needle moves upward, the sending unit is faulty and should be replaced. If the needle still does not move, either the wire to the gauge is broken (open circuit) or the gauge is faulty.