Coolant temperature sensor open circuit.

Possible Cause:-

Coolant temperature sensor wire harness not connected to Coolant temperature sensor.

Faulty coolant temperature sensor.

Poor wire harness connection at MECU.

Diagnosis:-

1. Check the coolant temperature wire harness connector connected to coolant temperature sensor on engine or
   not. Refer below photograph.

2. Check the coolant temperature sensor resistance by help of multimeter.At 80°C the approximate resistance of
sensor shall be 323Ω.

3. Check the circuit 4069 in cavity 17 & circuit 4303D in cavity 3 of MECU connector are connected properly or
not. In cavity 17 & Cavity 3 terminal back out should not there.

Corrective Action:-

1. Connect the wire harness with the Coolant temperature sensor.
2. Replace the faulty sensor.
3. Connect MECU with machine wire harness properly.