Engine Electrical System

Diagnostic trouble code: P0118“Over temperature indicated by engine coolant
temperature sensor”
Item
No.
Operation procedure
Inspection
results
Follow-up procedure
1
Connect the diagnostic tester and
adaptor, and turn the ignition switch to
“ON” position.
Proceed to next step.
Yes Proceed to Step 6
2
Observe the “coolant temperature” in
data flow to verify that it matches to the
engine temperature (the exact value is
determined by the engine temperature at
that time).
Note: If the indicated value is
maintained at -40 at that time, there ℃
may be some open malfunction occurs
in the circuit.
No Proceed to next step.
Yes Proceed to next step.
3
Disconnect the connector of the coolant
temperature sensor on the wiring
harness, inspect with multimeter to
verify that the resistance between 1#
and 2# pins of the sensor matches to the
temperature (see the related part of this
maintenance manual for reference).
No Replace the sensor.
Yes Proceed to Step 6
4
Disconnect the connector of the coolant
temperature sensor on the wiring
harness, inspect with multimeter to
verify that the voltage between 1# and
2# pins of this connector is about 5V.
No Proceed to next step.
Yes
Repair or replace the
wiring harness.
5
Check whether the circuits between 39#
and 35# pins of ECU and the 1# and 2#
pins of the sensor connector are short to
ground.
No Proceed to next step.
Yes
Refer to diagnosis
help.
6
Start up the engine, run at idle speed.
Observe the value of “Coolant
temperature” on the diagnostic tester to
verify that the indicated value is
increased along with the temperature
increase of the engine coolant.
No Replace the sensor.
E-25
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