P1483

Diagnostic Chart:

CIRCUIT DESCRIPTION
The PCM will richen the air/fuel ratio when a high coolant temperature is monitored. Called Hot Fuel Enrichment (HFE) this condition can cause exhaust emissions to exceed the federal emissions standards for this vehicle. This DTC is required in order to prevent HFE from being active during a skewed ECT sensor condition or during an actual cooling system condition that results in hot engine coolant. The PCM will calculate an engine coolant temperature value based on IAT, engine speed, vehicle speed and engine load. If the ECT sensor value is higher than the calculated coolant temperature during the Conditions for Running the DTC, this DTC sets and HFE is disabled.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0107, P0108, P0117, P0118, P0125, P0502, or P1108 are not set.
^ Engine coolant temperature is the same or less than 110°C (230°F) at startup.

OR

^ The engine coolant temperature is less than 104°C (219°F) anytime at startup.
^ Intake Air Temperature, Engine Load, Engine Speed and Vehicle Speed are all within a specific range.

CONDITIONS FOR SETTING THE DTC
The PCM determines the monitored engine coolant temperature (from the ECT sensor) is more than the calculated coolant temperature.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
^ The most likely cause of this DTC is a cooling system problem. Perform the Electric Cooling Fan Diagnosis and also visually inspect the cooling system for problems such as restricted radiator AIR flow. Refer to Engine Cooling for more cooling system diagnostic aids. Component Tests and General Diagnostics
^ The IAT sensor must indicate the actual ambient temperature to within 1 degree. If the IAT sensor is accurate the ECT sensor must be inaccurate. Test of the ECT sensor can be made by comparing actual coolant temperature to the ECT scan tool display.

Obtain actual coolant temperature using a thermometer located in the engine coolant. A test of the ECT sensors resistance may also be performed.

If the actual coolant temperature is the same as the ECT scan tool display then the engine was not allowed to cool completely. Allow the vehicle to cool and repeat the diagnostic table.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
3. Compares temperature readings of the ECT and IAT sensors.
4. Tests the temperature of the ECT sensor.