Toyota Corolla (E120): Circuit description
If the engine coolant temperature (ect) does not reach 75°c (167°f) despite sufficient warm – up time has elapsed.
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Dtc no |
Dtc detection condition |
Trouble area |
| P0128 | Condition (a), (b) and (c):
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Monitor description

The ecm estimates the engine coolant temperature (ect) based on starting temperature, engine loads, and engine speeds. The ecm then compares the estimated ect with the actual ect. When the estimated ect reaches 75 c (167 f) the ecm checks the actual ect. If the actual ect is less than 75 c (167 f), the ecm will interpret this as a fault in the thermostat or engine cooling system or thermostat and set a dtc.
Monitor strategy

Typical enabling conditions

Typical malfunction thresholds

Component operating range

Monitor result (mode 06 data)

Refer to page 05–27 for the detailed information on checking monitor status.
Other materials:
Inspection procedure
Hint:
if different dtcs related to different systems that have terminal e2
as the ground terminal are output
simultaneously, terminal e2 may be open.
If dtc p0441 (purge flow), p0446 (vsv for ccv), p0451, p0452 or p0453
(evaporative pressure
sensor) is output with dtc p0442 or p0456, ...
Toyota Safety Sense 3.0
The Toyota Safety Sense 3.0
consists of the driving
assist systems and contributes
to a safe and comfortable
driving experience:
WARNING
■Toyota Safety Sense 3.0
The Toyota Safety Sense 3.0
operates under the assumption
that the driver will drive safely,
and is designed to help reduce
the impact t ...
Inspection procedure
1 Check tvip ecu
Check that the operation of the tvip function is normal.
Hint:
with this inspection, the tvip ecu cpu can be diagnosed if it works normally or
not.
2 Check wire harness (tvip ecu integration relay)
Disconnect the tvip ecu and integration relay connectors.
ch ...


