
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
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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 circuitIndicators
The indicators inform the driver
of the operating state of the
vehicle's various systems.
Turn signal indicator
Headlight indicator
Tail light indicator
Headlight high beam indicator
Automatic High Beam
indicator
Fog light indicator (if
equipped)
Smart key system indicator*
1
Cruise control ...
Removal and installation of fuel control
parts
Place for removing and installing fuel
system parts
Work in a location with good air ventilation that
does not have welders, grinders, drills, electric
motors, stoves, or any other ignition sources.
Never work in a pit or near a pit as vaporized
fuel will collect in those places.
...
Automatic air conditioning
system
Air outlets and fan speed are automatically adjusted according
to the temperature setting.
Air conditioning controls
Automatic mode switch
Left-hand side temperature control knob
Right-hand side temperature control knob
"SYNC" switch
"OFF" switch
Windshield defogger switch
Rear window and o ...