
Hint:
This dtc relates to the thermostat.
Description
This dtc is set when the engine coolant temperature (ect) does not reach 75°c (167°f) despite sufficient engine warm-up time having elapsed.

Monitor description

The ecm estimates the ect based on the starting temperature, engine loads, and engine speeds. The ecm then compares the estimated temperature 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 interprets this as a malfunction in the thermostat or the engine cooling system and sets the dtc.
Monitor strategy
![]()

Typical enabling conditions

Typical malfunction thresholds

Inspection procedure
Hint:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

Hint:
If any dtcs other than p0128 are output, troubleshoot those dtcs first.


Standard value: 80 to 84°c (176 to 183°f)
Hint:
In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.

Insufficient coolant temperature for closed loop fuel control
Oxygen sensor circuitRear center seat outer belt assembly
Components
Removal
Caution:
Wait at least 90 seconds after disconnecting the cable
from the negative (-) battery terminal to prevent airbag
and seat belt pretensioner activation.
Remove shoulder belt anchor cover rh
Using a screwdriver, remo ...
Closing the fuel tank cap
After refueling, turn the fuel tank
cap until you hear a click. Once
the cap is released, it will turn
slightly in the opposite direction.
Caution
When replacing the fuel tank cap
Do not use anything but a genuine toyota fuel tank cap designed for
your
vehicle. Doing so may cause a fire ...
Before driving
Floor mat
Use only floor mats designed specifically for vehicles of the same
model and model year as your vehicle. Fix them securely in place
onto the carpet.
Insert the retaining hooks (clips)
into the floor mat eyelets.
Turn the upper knob of each
retaining hook (clip) to secure
t ...