International DT466 – ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS – EWPS Diagnostic Trouble Codes (DTCs) - Diesel Engines Troubleshooting (2024)

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DTCs are read using the EST or by counting the flashes from the amber and red ENGINE lamp.

DTC 323
ECT below warning/critical level
• DTC 323 is set by the ECM when coolant is low. When the EWPS mode is 3-way protection and DTC 323 is active, the engine will shutdown. The ECM will log the engine hours and odometer reading at the time of occurrence. After the shutdown, the engine can be restarted for thirty seconds. When the coolant has returned to correct levels, DTC 323 will become inactive.

NOTE: If coolant level is correct, see “ECL Sensor” (page 370). An ECL signal shorted to ground can cause DTC 323.

DTC 321
ECT above warning level
• DTC 321 is set by the ECM when the engine coolant temperature is above 110 °C (230 °F). The ECM illuminates the red ENGINE lamp and sounds the audible alarm. When the temperature drops below 110 °C (230 °F) the DTC will become inactive. For diagnostics, see “Engine Symptoms Diagnostics” – Section 4 (page 101).
• For high altitude applications (103 kPa [15 psi] radiator cap), DTC 321 is set by the ECM when the engine coolant temperature is above 113 °C (235 °F). When the temperature drops below 113 °C (235 °F) the DTC will become inactive.

DTC 322
ECT above critical level
• DTC 322 is set by the ECM when the engine coolant temperature is above 112 °C (234 °F). The ECM illuminates the red ENGINE lamp and sounds the audible alarm. When the temperature drops below 112 °C (234 °F) the DTC will become inactive. For diagnostics, see “Engine Symptoms Diagnostics” – Section 4 (page 101).
• For high altitude applications (103 kPa [15 psi] radiator cap), DTC 321 is set by the ECM when the engine coolant temperature is above 116 °C (241 °F). When the temperature drops below 116 °C (241 °F) the DTC will become inactive.

DTC 325
Power reduced, matched to cooling system performance
• DTC 325 is set by the ECM when the cooling system temperature exceeds 107 °C (225 °F). At this temperature the ECM will reduce the fuel delivered to the engine. When the temperature drops below 107 °C (225 °F) the DTC will become inactive and the engine will return to normal operation.

For each Celsius degree of temperature the fuel will be reduced by 6 percent. For each Fahrenheit degree of temperature the fuel will be reduced by 3 percent. This reduces the heat produced by the engine and reduces the burden on the cooling system. The vehicle speed will also be reduced and allow the operator to downshift and
increase the efficiency of the cooling system. As the temperature is reduced, the compensation level is reduced until the temperature drops below 107 °C (225 °F) and normal operation is resumed.

For high altitude applications (103 kPa [15 psi] radiator cap), as the temperature is reduced, the compensation level is reduced until the temperature drops below 111 °C (232 °F) and normal operation is resumed.
DTC 325 does not illuminate the ENGINE warning lamp.

DTC 316
ECT unable to reach commanded set point
NOTE: DTC 316 only indicates the engine has not been able to reach operating temperature. It does not indicate an electronic fault.
• DTC 316 is set if the engine does not reach operating temperature. DTC 316 will only be set with engines that have Cold Ambient Protection (CAP) strategy enabled. DTC 316 is set after the engine has run for more than 120 minutes
and has not exceeded 66 °C (151 °F) for engine coolant temperature. DTC 316 can be cleared with the EST.

• DTC 316 can be set due to any of the following conditions:
• Extended idle time
• Cold ambient temperatures (may require use of winter front)
• Thermostat stuck in open position
• Incorrectly plumbed cooling system (thermostat bypassed)
• Auxiliary heater cores cooling off engine (school bus application)
• Fan clutch locked on

DTC 313
EOP below warning level
• DTC 313 is set by the ECM when the oil pressure has dropped below the warning level. The specification for the warning level is:
• 34 kPa (5 psi) @ 700 rpm
• 69 kPa (10 psi) @ 1400 rpm
• 138 kPa (20 psi) @ 2000 rpm
The ECM illuminates the red ENGINE lamp and sounds an audible alarm.
For diagnostics, see “Engine Symptoms Diagnostics” – Section 4 (page 101). DTC 313 can be set due to a failed EOP sensor sending an incorrect signal. To confirm this, compare actual oil pressure to the reading on the data list of the EST. Low oil pressure due to inoperative mechanical components will also set DTC 313.

DTC 314

EOP below critical level
• DTC 314 is set by the ECM when the oil pressure has dropped below the critical level. The specification for the critical level is:
• 14 kPa (2 psi) @ 700 rpm
• 83 kPa (12 psi) @ 1400 rpm
• 152 kPa (22 psi) @ 2000 rpm
The ECM flashes the red ENGINE lamp and sounds an audible alarm. See “Engine Symptoms Diagnostics” – Section 4 (page 101).
• DTC 314 can be set due to a failed EOP sensor sending an incorrect signal. To confirm this,
compare actual oil pressure to the reading on the data list of the EST. Low oil pressure due to inoperative mechanical components will also set DTC 313.

DTC 315
Engine speed above warning level
• DTC 315 is set by the ECM when the engine rpm has exceeded 3400 rpm.
• DTC 315 can be set due to any of the following conditions:
• Excessive engine speed in an unintended downshift.
• Steep acceleration downhill without correct brake application.
• External fuel source being ingested into air intake system.
• When DTC 315 is active the amber ENGINE lamp is illuminated. The engine hours and miles of the last two over speed occurrences will be recorded in the engine event log.