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Home >> Acura >> 2004 >> 3.5RL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Performance System Self-Diagnostics >> Diagnostic Tests >> DTC P0116: Engine Coolant Temperature (ECT) Sensor Circuit Range/Performance Problem (2004 3.5RL) >> Diagnostic Procedure
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Diagnostic Procedure

  1. Turn ignition switch off. Using HDS (Honda Diagnostic System) or scan tool, check ECT output temperature or voltage. If ECT output temperature is about 176°F (80°C) or higher, or 0.86 volt or less, go to next step. If ECT output temperature is not about 176°F (80°C) or higher, or not 0.86 volt or less, go to step  3 .
  2. Note current coolant temperature. Turn ignition switch off. Cool engine for one hour, and recheck ECT output temperature or voltage with scan tool or HDS. If ECT changes 3.6°F (2°C) or more, problem is intermittent. System is okay at this time. Check thermostat and cooling system. Repair as necessary. If ECT does not change 3.6°F (2°C) or more, replace ECT sensor.
  3. Note current coolant temperature. Start engine. Hold engine speed at 3000 RPM with no load and transmission in Park or Neutral until radiator fan comes on, then allow engine to idle. Check ECT output temperature or voltage with scan tool or HDS. If ECT changes 3.6°F (2°C) or more, problem is intermittent. System is okay at this time. Check thermostat and cooling system. Repair as necessary. If ECT does not change 3.6°F (2°C) or more, replace ECT sensor.
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