P011A - Engine Coolant Temperature Sensor 1/2 Correlation
Engine Coolant Temperature is monitored to allow the ECM to accurately adjust fueling and emission control systems, it will also normally be used to control cooling fan operation. In some cases more than one Engine Coolant Temperature sensor can be fitted, this may be to monitor different banks on a V engine or to monitor different parts of the engine, (cylinder head and cylinder block)
Fault Code Explained
The ECM has detected that the sensors are providing conflicting temperature information when they should be the same.
If possible use a diagnostic computer to view live data readings for the sensors and compare to actual coolant temperature to establish which sensor is providing the incorrect information. Carry out wiring tests on the sensor circuit that is reading incorrectly.