Toyota Corolla (E120): Circuit description
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):
|
|
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

Typical enabling conditions

Typical malfunction thresholds

Component operating range

Monitor result (mode 06 data)

Refer to page 05–27 for the detailed information on checking monitor status.
Other materials:
Ecm (1zz–fe)
Replacement
1. Disconnect battery negative terminal
2. Remove glove compartment door assy
3. Remove ecm
Remove the 2 clips using a clip remover. Then, open the
cover.
Disconnect the 4 ecm connectors.
remove the wire harness from the wire harness clamp.
Remove the 2 ...
Inspection procedure
Hint:
if dtc p0441 (purge flow), p0446 (vsv for ccv or vsv for pressure
switching valve), p0451, p0452
or p0453 is output with dtc p0442 or p0456 , first troubleshoot
dtc p0441, p0446, p0451, p0452 or p0453. If no malfunction is detected,
troubleshoot dtc
p0442 or p0456 next.
...
Diagnostic trouble code chart
Hint:
as for the vehicle for mexico, refer to repair manual 2003 corolla (pub. No.
Rm938u).
Parameters listed in the chart may not be exactly the same as your readings due
to the type of instrument
or other factors.
If a malfunction code is displayed during the dtc check in the check mod ...


