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:
Manual air conditioning system∗
Air conditioning controls
► Heater
► Air conditioning system
■ Adjusting the temperature setting
► Heater
To adjust the temperature setting, turn the
dial clockwise to increase the temperature.
► Air conditioning system
To adjust the temperature setting, tu ...
Circuit description
Refer to dtc p0115
Dtc no.
Dtc detection condition
Trouble area
P0125
If the engine coolant temperature (ect) was less than –6.6 °C
(20 °F) when starting the engine, and 20 minutes after the engine
start, the ect sensor still indicates below 20 °C (68 ...
Changing the engine switch positions
1 “LOCK”
The steering wheel is locked and the key can be removed. (Vehicles with an automatic
transmission or continuously variable transmission: The key can be removed only
when the shift lever is in P.) 2 “ACC”
Some electrical components such as the audio system can be used.
3 “ON ...


