DTC EFI-251

2-5-1 OUTSIDE TEMPERATURE SENSOR SIGNAL





Condition

- Diagnostic trouble code (DTC) EFI-251 is stored if the engine control module (ECM) receives a signal from the outside temperature sensor corresponding to a temperature below -45°C (-49°F) (signal too high), or higher than +14O°C (284°F) (signal too low).
- Diagnostic trouble code (DTC) EFI-251 is stored if the signal is unstable for 25 seconds (sporadic signal).

Substitute Value
- The engine control module (ECM) adopts an outside temperature of +20°C (68°F).

Possible Source

Signal too High:

- Open-circuit in signal cable or ground lead
- Short-circuit to supply voltage in signal cable
- Contact resistance in terminals
- Defective outside temperature sensor.

Signal too Low:

- Short-circuit to ground in signal cable
- Defective outside temperature sensor.

Signal Sporadic:

- Loose connection
- contact resistance in terminals
- Defective outside temperature sensor.

Fault Symptom(s)

- None.