Toyota PRIUS C 2019 Manual page 424

424
7-3. Do-it-yourself maintenance
Coolant
Engine coolant reservoir

The coolant level is satisfactory if it is between the "FULL" and "LOW"
lines on the reservoir when the engine is cold.
Reservoir cap
1
"FULL" line
2
"LOW" line
3
If the level is on or below the
"LOW" line, add coolant up to the
"FULL" line. (P. 526)
Power control unit coolant reservoir

The coolant level is satisfactory if it is between the "F" and "L" lines on
the reservoir when the hybrid system is cold.
Reservoir cap
1
"F" line
2
"L" line
3
If the level is on or below the "L"
line, add coolant up to the "F" line.
(P. 526)
PRIUS c_U