Engine Coolant Temperature Gauge

Description

Engine Coolant Temperature Gauge
The coolant temperature gauge indicates the temperature of the engine coolant. When the engine reaches normal operating temperature, the gauge rests at the mid-point of the temperature scale.

If the engine coolant temperature becomes too high, the pointer will rise to the red segment of the scale to warn of an engine cooling fault. At this position the engine coolant temperature is too high and continued operation could result in engine damage; the vehicle should be stopped as soon as possible.

The engine coolant temperature gauge is driven by a CAN message from the ECM. The ECM derives the engine coolant temperature from an engine coolant temperature (ECT) sensor.

The temperature gauge is fitted with a return magnet causing the gauge to return to zero when the ignition is switched off. The coolant temperature gauge is only operative when the ignition switch is in position II or when diagnostics are selected.

When the engine is hot, the gauge will display normal temperature until the engine has been running for more than 15 seconds. This prevents the gauge moving to the red sector of the gauge if the ignition is turned off and then on after a journey. If the engine is not started, the coolant pump will not circulate coolant and local hot spots occur in the engine and give an incorrect temperature reading. The 15 second delay allows for the engine to be started and coolant circulated, allowing the gauge to display the true average temperature.

Coolant Temperature Engine Coolant Temperature
Gauge Needle Position degrees C (degrees F)
Cold 40 (104)
Normal 75 - 115 (167 - 239)
Hot (Red zone) 120 (248)