DTC P0117/P0118 ENGINE HEAD TEMPERATURE (EHT) SENSOR
Circuit Description
The EHT sensor uses a thermistor to control signal
voltage to the ECM. The ECM applies 5 volts on the
sensor circuit. Sensor resistance changes as ambient
temperature changes, which in turn affects the voltage
return to the ECM.
Diagnostic Aids
Check for the following conditions:
1. Poor ECM connection.
2. Inspect wire harness connectors for backed out
terminals, improper mating, broken locks, improperly
formed or damaged terminals, and poor terminal to
wire connection.
3. Damaged wire harness and/or connectors. If harness
appears to be OK, shake or wiggle wire harness
and/or connector with DVOM or Diagnostic Tool
connected. Radical voltage changes or a change in
the EHT sensor display can indicate the location of
the fault condition.
Always clear DTCs after performing repairs.
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