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Home >> Jeep >> 2005 >> Wrangler Rubicon, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 490 (Powertrain Diagnostic Procedures - Diesel) >> Diagnostic Information And Procedures >> DRIVEABILITY - Diesel - Diagnostic Tests >> P0128-Engine Coolant Temp Sensor Engine Is Cold Too Long >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURES - P0128-ENGINE COOLANT TEMP SENSOR ENGINE IS COLD TOO LONG

TEST ACTION APPLICABILITY
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NOTE: The best way to diagnose this DTC is to allow the vehicle to remain outside overnight in order to have a completely cold soaked engine.
NOTE: Extremely cold outside ambient temperatures may cause this DTC to set.
Verify that the coolant level is correct.Start the engine.With the DRBIII®, set the engine RPM to 1500 and allow the engine to warm up for 10-15 minutes.With the DRBIII®, monitor the Engine Coolant Temperature value during the warm up cycle. Make sure the transition of temperature change is smooth.Did the engine temperature reach a minimum of 80°C (176°F)?Yes --> Test Complete.No --> Refer to the Service Information for cooling system performance diagnosis. The most probable cause is a Thermostat problem. Also, refer to any related TSBs.Perform ROAD TEST VERIFICATION - VER-2 .
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