
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 circuitHigh pitched horn
Components
Removal
Remove radiator support opening cover
(see page et-4)
Remove front fender liner lh (see page et-4)
Remove front fender liner rh (see page et-4)
Remove front bumper cover (see page et-5)
Remove high pitched horn
Disconnect the horn connector.
Remove t ...
Rear axle hub and bearing
Components
On-vehicle inspection
Remove rear wheel
Disconnect rear drive shaft assembly lh
(for 4wd)
Disconnect the drive shaft (see page ds-69).
Remove rear disc brake cylinder assembly
lh (see page br-55)
Remove rear disc (see page br-57)
Check bearing backlash a ...
Removal
Hint:
Use the same procedures for the rh side and lh side.
The procedures listed below are for the lh side.
Remove front pillar cover sub-assembly upper lh
Using a moulding remover, detach the 3 clips and
remove the pillar cover.
...