Toyota Corolla Quiz
Diagnostics

Circuit description

In this manual: Diagnostics
Introduction — 31Preparation — 32Service specifications — 19Diagnostics — 497Engine control system — 6Fuel — 13Emission control — 28Exhaust — 3Cooling — 13Lubrication — 7Ignition — 3Starting & charging — 13Front suspension — 12Rear suspension — 9Tire & wheel — 1Drive shaft / propeller shaft — 15Brake — 42Automatic transmission / trans — 47Clutch — 19Steering column — 9Power steering — 11Heater & air conditioner — 20Supplemental restraint system — 27Seat belt — 12Lighting — 18Wiper & washer — 9Audio & visual — 12Wiring — 1Communication system — 1Windshield/windowglass/mirror — 31Seat — 10Theft deterrent & door lock — 10Sliding roof/convertible — 8Engine hood/door — 12Exterior/interior trim — 20Vehicle control system — 1Cruise control — 5Maintenance — 8
3steps
~18min
2/5difficulty
Done 0 of 3

If the engine coolant temperature (ect) does not reach 75°c (167°f) 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 75°c (167°f)
  • Thermostat
  • cooling system
  • engine coolant temperature sensor
  • ecm
Monitor description
Toyota Corolla. 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
Toyota Corolla. Monitor strategy
Typical enabling conditions
Toyota Corolla. Typical enabling conditions
Typical malfunction thresholds
Toyota Corolla. Typical malfunction thresholds
Component operating range
Toyota Corolla. Component operating range
Monitor result (mode 06 data)
Toyota Corolla. Monitor result (mode 06 data)

Refer to page 05–27 for the detailed information on checking monitor status.

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A quick Toyota Corolla quiz: every answer comes with an explanation and a link to the manual page.