Adjust the engine idle speed periodically on the engine at normal operating temperature.
To adjust the idle speed:

Engine oil and filter change
Throtile cable playEngine coolant
Coolant level
The engine coolant solution
should be between "f" (full) and
"1..:' (Low) level lines on the engine
coolant reservoir. If the level is
lower than "1..:' (Low) level line,
bring it up to "f" (full) level by adding
50:50 mixture of distilled water ...
Radiator cap inspection
Inspect the radiator cap in the following procedures:
remove the radiator cap. Refer to “cooling circuit inspection” .
Attach the radiator cap (1) to the radiator tester (2)
as shown.
Slowly apply pressure to the radiator cap.
If the radiator cap does not hold the pre ...
DTC “c23” (p1651-h/l): to sensor circuit
malfunction
Detected condition and possible cause
Detected condition
Possible cause
C23
The sensor voltage should be the
following for 2 sec. And more, after ignition
switch is turned on.
0.2 V ≤ Sensor voltage < 4.8 V
To sensor circuit open or shor ...