Hino P2185 Fault Code: Engine coolant temperature sensor 2 – Out of range (Out of range high)

TECHNICAL DESCRIPTION 

Engine coolant temperature sensor 2 is installed in a thermostat case and constantly measures the engine coolant temperature.

DESCRIPTION OF MALFUNCTION

Engine coolant temperature cannot be correctly recognized

DTC SET CONDITION

DTC Detection Condition: 

• Starter switch is inactive to the “ON” position
• Battery voltage is in the range of 10 V to 16 V
• Above conditions continue for at least 5 seconds

Judgment Criteria:

Engine coolant temperature sensor 2 output is at least 4.77 V (-37°C {-35°F}), and this condition continues for at least 3 seconds. 

RESET CONDITION

After restoration to normal condition

INDICATION, WARNING OR SYSTEM CONTROL REGULATION WHEN THE DTC IS SET

Symptoms on the vehicle due to backup control (fail safe function)

• Engine output is insufficient
• Cruise control does not work
• Idling stop system does not work
• Vehicle start control does not work

PRE-INSPECTION WORK

Check that the battery voltage is in the normal range

AFTER-INSPECTION WORK 

• Clear all past DTC. 
• Check that no DTC is detected after test drive

POSSIBLE CAUSES 

• Abnormal resistance of the sensor
• Engine ECU sensor power supply failure or internal circuit failure
• Harness disconnection or short-circuit
• Looseness or poor contact of connector
• Sensor internal short-circuit

INSPECTION PROCEDURE

TROUBLESHOOTING STEPS

Step 1: Inspect the engine coolant temperature sensor 2 connector

Check the connection of the engine coolant temperature sensor 2 connector (Looseness and poor contact)

Were any failures found?

Step 2: Inspect the engine coolant temperature sensor 2

1. Check the installation of the engine coolant temperature sensor 2
2. Make sure there is no dirt or damage to the engine coolant temperature sensor 2

Were any failures found?

Step 3: Inspect the engine coolant temperature sensor 2 unit

1. Set the starter switch to the “LOCK” position
2. Disconnect the engine coolant temperature sensor 2 connector
3. Use the electrical tester to measure the resistance between the terminals of the engine coolant temperature sensor 2 connector

Do the measurements meet the standard value?

Step 4: Inspect the engine coolant temperature sensor 2 power supply

1. Set the starter switch to the “ON” position
2. Use the electrical tester to measure the voltage between the terminals of the engine coolant temperature sensor 2 vehicle-side connector

Do the measurements meet the standard value?

Step 5: Inspect for short-circuit of the engine coolant temperature sensor 2 wire harness

1. Set the starter switch to the “LOCK” position. 
2. Connect the signal check harness to the engine ECU vehicle-side harness. (Do not connect harness to the ECU)
3. Use the electrical tester to measure the resistance between each terminal in the engine ECU (signal check harness) and ground

Do the measurements meet the standard value?

Step 6: Inspect disconnection of the wire harness of engine coolant temperature sensor 2

1. Connect the engine coolant temperature sensor 2 connector
2. Use the electrical tester to measure

Do the measurements meet the standard value?

Step 7: Check the DTC detected (Engine ECU) [Diagnostic Tool]

1. Warm-up the engine. (Engine coolant temperature: 60°C {140°F} or more)
2. Stop the engine and set the starter switch to the “LOCK” position
3. Connect the vehicle to the diagnostic tool
4. Set the starter switch to the “ON” position
5. Select [Engine] and check if DTC P2184 or P2185 has been detected

Has DTC P2184 or P2185 been detected?

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