P1544

DTC P1544: DOR Radiator Tampering Monitor (Temperature Check Before Thermostat Open)

RADIATOR SENSOR CIRCUIT
Refer to P1540

CIRCUIT OPERATION
Refer to P1540

MONITOR EXECUTION
Once per driving cycle

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable

Sensor (The sensor below is determined to be normal)
- Not applicable

DTC SET CONDITIONS

Logic Flow Chart

Logic Flow Chart:

Check Condition
- Battery positive voltage is higher than 11 volts.
- Intake air temp from 0 °C (32 °F) to 40 °C (104 °F).
- Engine coolant temperature is less than 40 °C (104 °F) when at engine start.
- The engine coolant temperature - intake air temperature is 5 °C (41 °F) or less at engine start.
- Vehicle speed is lower than 1.5km/h (1mph).

Judgement Criteria
- When the output temperature of the radiator sensor before the thermostat valve is opened is high, the sensor is defective.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD - II Drive Cycle

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
- Tampering of the DOR radiator
- Malfunction of the thermostat
- Engine coolant is insufficient or has deteriorated.
- Malfunction of the water pump
- Malfunction of the PCM

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Check the thermostat.

- Thermostat inspection (Refer to Thermostat inspection). Service and Repair

Q: Is the check result normal?

YES : Go to Step 2.

NO : Repair it. Then go to Step 4.

STEP 2. DOR radiator sensor installation check

- Check that the sensor is installed securely and operates normally.

Q: Is the check result normal?

YES : Go to Step 3.

NO : Replace the DOR radiator. Then go to Step 4.

STEP 3. Replace the DOR radiator

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD - II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1544 set?

YES : Replace the PCM. Then go to Step 4.

NO : The procedure is complete.

STEP 4. Perform the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD - II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1544 set?

YES : Repeat the troubleshooting.

NO : The procedure is complete.