[Opie]

Sounds like a harness or ECM issue....check resistance and voltage.

DTC P0118 ENGINE COOLANT TEMPERATURE CIRCUIT HIGH INPUT CIRCUIT DESCRIPTION
The resistance of the thermistor built into the E.F.I. water temperature sensor changes as the engine coolant temperature changes. The E.F.I. water temperature sensor is connected to the engine control computer in the same way the inlet air temperature sensor is connected.
NOTE:
When this DTCs is stored, the engine control computer enters fail-safe mode. The engine control computer fixes the specified engine coolant temperature at 70°C {158°F} during the fail-safe mode operation. The engine control computer continues fail-safe mode operation until the normal condition is restored.
DTC No.
P0118
E.F.I. water temperature sensor voltage is 4.698 V or more for 0.5 seconds or longer.
(1 trips detection logic)
Suspect Parts:
• Open in E.F.I. water temperature sensor circuit
• E.F.I. water temperature sensor
• ECM
MONITOR DESCRIPTION
The E.F.I. water temperature sensor is used for monitoring a coolant temperature. The resistance of the thermistor integrated into the E.F.I. water temperature sensor changes as the engine coolant temperature changes. The lower the coolant temperature, the greater the thermistor resistance, and the higher the intake air temperature, the lower the thermistor resistance.
The resistance indicates the output voltage from the sensor. The ECM monitors the sensor voltage and use the value for calculating a engine coolant temperature. When the sensor output voltage falls out of the normal operation range, the ECM identifies this as an abnormal condition in the E.F.I. water temperature sensor and stores the DTC.
MONITOR STRATEGY
P0118: Engine coolant temperature sensor range check (High voltage)
Required Sensors/Components (Main)
E.F.I. water temperature sensor
Required Sensors/Components (Related)
-
Frequency of Operation
Continuous
Duration
0.5 seconds
MIL Operation
Immediately
Sequence of Operation
None
TYPICAL ENABLING CONDITIONS
Overlap prohibited DTC
None
TYPICAL MALFUNCTION THRESHOLDS
P0118
E.F.I. water temperature sensor voltage [Engine Coolant Temp.]
4.698 V or more [-46.2°C {-51°F} or more]
OPERATION RANGE
E.F.I. water temperature sensor voltage [Engine Coolant Temp.]
0.357 to 4.688 V [-43.85 to 136.12°C {-47 to 251°F}]