Honda Civic Service Manual page 264

DTC P0116: ECT Sensor Range/Performance
Problem
NOTE: lf DTC P0117 and/or P0118 are stored at the
same time as DTC P0116, troubleshoot those DTCS first,
then recheck for DTC P0116,
1. Stanthe engine. Hold the engine at 3,000 rpm with
no load {in neutral) until the radiator fan comes on,
then let it idle.
2. Check the ECT with the scan tool.
l s 1 7 6 - 2 1 2 ' F ( 8 0 1 0 0 " C ) o r 0 . 5 0 . 8 V
indicated?
YES Intermittent failure. system is OK at this time.
Check the thermostat and the cooling system.l
NO-Checkthe thermostat and the cooling system.
lf they are OK, replace the ECT sensor.l
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