Diagnostic Trouble Code (DTC) Information

Condition:
Diagnostic trouble code (DTC) CI-121 is stored if the combined instrument panel receives a signal from the engine control module (ECM) corresponding to a temperature below -45 °C (-49 °F) (low frequency) or higher than +150 °C (302 °F) (high frequency).

Possible Source:

NOTE: An accessory immobilizer with separate plastic key can cause diagnostic trouble code (DTC) CI-121 if the ignition is switched on before the immobilizer has been deactivated.
This type of diagnostic trouble code (DTC) is not included in fault-tracing.

- Short-circuit to battery voltage in signal cable
- Short-circuit to ground in signal cable
- Open-circuit in signal cable.
- Fault in ignition/fuel injection system.
- Large contact resistance.
- Loose connections.

Fault Symptom(s):
The engine coolant temperature (ECT) gauge constantly displays lowest temperature.

Start fault-tracing with DB. "Faulty Signal". Faulty Signal