DTC EFI-123

1-2-3 ENGINE COOLANT TEMPERATURE SENSOR, SIGNAL





Trouble Code Conditions
- Diagnostic trouble code (DTC) EFI-123 is stored if the engine coolant temperature (ECT) sensor signal corresponds to a temperature lower than -44°C (high signal) or higher than +148°C (low signal). Depending on starting temperature, there should be a set time between the engine being started and it reaching +28°C, if this time is exceeded diagnostic trouble code EFI-123 is stored.

Substitute value(s)
- When the engine is started a substitute value of +20°C is assumed, after the engine is started a value of +83°C is assumed.
- With ignition on the engine coolant fan operates at low-speed.
- When the engine is running the engine coolant fan operates at high-speed.
- When the engine is switched off the engine coolant fan runs on for a further 3 minutes.
- Idle air trim adaptation disabled.
- Long-term fuel trim disabled.
- Leakage diagnostic is turned off.

Possible source(s)
Signal too high:
- Short-circuit to supply voltage in signal cable.
- Open-circuit in signal or ground cable.
- Contact resistance in terminals.
- Defective engine coolant temperature sensor.

Signal too low:
- Short-circuit to ground in signal cable.
- Defective engine coolant temperature sensor.

Faulty signal:
- Defective engine coolant temperature sensor.
- Defective coolant thermostat.
- Contact resistance in terminals.
- Short-circuit between signal cable an another cable.

Fault symptom(s)
- Difficulty in starting in certain temperature ranges.
- With ignition on the engine coolant fan operates at low-speed.
- When the engine is running the engine coolant fan operates at high-speed.
- When the engine is switched off the engine coolant fan runs on for a further 3 minutes.