WOMS
C code chassis Medium severity

C1774 Coolant Temp Out of Range

The OBD2 code C1774 indicates that the coolant temperature sensor is reading a temperature that is outside the expected range, which may suggest a malfunction in the sensor or the cooling system

Definition

The OBD2 code C1774 indicates that the coolant temperature sensor is reading a temperature that is outside the expected range, which may suggest a malfunction in the sensor or the cooling system

Common causes

  • Faulty coolant temperature sensor
  • Wiring issues or damaged connectors
  • Engine overheating
  • Low coolant level
  • Faulty engine control module (ECM)
  • Thermostat malfunction
  • Air pockets in the cooling system
  • Incorrect coolant type or mixture

Common misdiagnoses

  • Faulty coolant temperature sensor
  • Thermostat malfunction
  • Wiring issues or short circuits
  • Engine overheating
  • Faulty engine control module (ECM)
  • Air pockets in the cooling system
  • Incorrect coolant type or mixture
  • Radiator issues

Troubleshooting steps

  1. 1. Check Coolant Level

    Ensure that the engine coolant is at the proper level. Low coolant can lead to incorrect temperature readings

  2. 2. Inspect Coolant Condition

    Look for signs of contamination or degradation in the coolant. Old or contaminated coolant can affect temperature readings

  3. 3. Examine the Coolant Temperature Sensor (CTS)

  4. 4. Check the wiring and connectors for damage, corrosion, or loose connections

  5. 5. Test the sensor using a multimeter to ensure it is functioning correctly. Compare the resistance readings to the manufacturer's specifications at various temperatures

  6. 6. Inspect the Engine Wiring Harness

    Look for any damaged or frayed wires in the engine wiring harness that could affect the signal from the coolant temperature sensor

  7. 7. Check for Engine Overheating

    If the engine is overheating, it could trigger this code. Inspect the cooling system for issues such as a faulty thermostat, water pump, or radiator

  8. 8. Test the Thermostat

    A stuck-open or stuck-closed thermostat can cause incorrect coolant temperature readings. Test or replace the thermostat if necessary

  9. 9. Scan for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes that may provide more context for the issue

  10. 10. Inspect the Engine Control Module (ECM)

    In rare cases, the ECM may be malfunctioning. Check for software updates or reprogramming if necessary

  11. 11. Clear the Code and Test Drive

    After performing any repairs, clear the code and take the vehicle for a test drive to see if the code returns

  12. 12. Consult Repair Manual

    If the issue persists, refer to the vehicle's repair manual for specific diagnostic procedures related to the coolant temperature sensor and related systems. If you're not comfortable performing these steps yourself, it's advisable to consult a professional mechanic for a thorough diagnosis and repair