Toyota Tacoma manuals

Toyota Corolla Repair Manual: Circuit description

If the engine coolant temperature (ect) does not reach 75c (167f) despite sufficient warm up time has elapsed.

Dtc no

Dtc detection condition

Trouble area

P0128 Condition (a), (b) and (c):
  1.  cold start
  2.  after engine is warmed up
  3.  engine coolant temperature is less than 75c (167f)
  • Thermostat
  • cooling system
  • engine coolant temperature sensor
  • ecm

Monitor description

The ecm estimates the engine coolant temperature (ect) based on starting

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 enabling conditions

Typical malfunction thresholds

Typical malfunction thresholds

Component operating range

Component operating range

Monitor result (mode 06 data)

Monitor result (mode 06 data)

Refer to page 0527 for the detailed information on checking monitor status.

Refer to page 0527 for the detailed information on checking monitor status.

Coolant thermostat (coolant temperature below thermostat regulating temperature)
Dtc p0128 coolant thermostat (coolant temperature below thermostat regulating temperature) Hint: this is the purpose of the thermostat malfunction detection. ...

Inspection procedure
Hint: read freeze frame data using the hand-held tester or the obd ii scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is usefu ...

Other materials:

Bluetooth (Multimedia system)
Bluetooth ■When using the Bluetooth audio system ●In the following conditions, the system may not function. If the portable audio player is turned off If the portable audio player is not connected If the portable audio players battery is low ●There may be a delay if ...

Using the AUX port
This port can be used to connect a portable audio device and listen to it through the vehicles speakers. Press until AUX is displayed. Connecting a portable player ■Operating portable audio devices connected to the audio system The volume can be adjusted using the vehicle's audio ...

Starting the engine
1 Check that the parking brake is set. ► Vehicles without a multi-information display 2 Continuously variable transmission: Check that the shift lever is set in P. Firmly depress the brake pedal. Manual transmission: Check that the shift lever is set in N. Firmly depress the clutch peda ...

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