If the reading is within the standard, but the problem still exists, replace the ECU (see ECU Removal/Installation in the Fuel System (DFI) chapter).
Water Temperature Sensor Circuit

1. ECU
2. Water Temperature Sensor
Water Temperature Sensor Output Voltage InspectionECU Communication Error (Service Code 39)
ECU Communication Line Inspection
When the data is not sent from the ECU to the meter unit
for more than about 10 seconds, the service code 39 is
displayed.
The data is sent through the CAN communication line.
The service code 39 is detected with the meter unit.
When the user mode, this commun ...
Tire Tread Wear Inspection
As the tire tread wears down, the tire becomes more susceptible
to puncture and failure. An accepted estimate is
that 90% of all tire failures occur during the last 10% of tread
life (90% worn). So it is false economy and unsafe to use
the tires until they are bald.
Measure the tread depth a ...
Check 3-5: Warning Indicator Light (Red LED) (Oil Pressure Warning)
Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [10] to the battery (–) terminal.
Check that the oil pressure warning symbol [A] and the
warning indicator light (Red LED) [B] go on.
If the indicator light does not go on, replace the meter unit.
...