DTC P0116 (TW_Low): ECT Sensor Circuit Low Input (Legacy)

1998 Subaru Forester L, StandardSECTION DTC P0116 (TW_Low): ECT Sensor Circuit Low Input (Legacy)
  1. Turn ignition off. Connect scan tool. Start engine. Observe coolant temperature display. If value is more than 300°F (150°C), go to next step. If displayed value is less than 300°F (150°C), check for poor contact in PCM and ECT sensor connectors or wiring.
  2. Turn ignition off. Remove air intake duct. Remove idle air control solenoid valve by-pass air hose. Disconnect ECT sensor connector. Turn ignition on. If displayed value is less than -40°F (-40°C), replace ECT sensor. If displayed value is more than -40°F (-40°C), repair short circuit in wiring between ECT sensor and PCM connectors.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.