Toyota Corolla (E120): 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 useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air–fuel ratio was lean or rich, etc. At the time of the malfunction.
1 Check cooling system
- Check that there is a defect in the cooling system which causes overcool, such as abnormal radiator fan operation, modified cooling system and so on.


2 Inspect thermostat


3 Check other dtc output(in addition to dtc p0128)
- Connect the hand–held tester or the obd ii scan tool to the dlc3.
- turn the ignition switch on and push the hand–held tester or the obd ii scan tool main switch on.
- select the item ”diagnosis / enhanced obd ii / dtc info / current codes”.
- read the dtcs.
Result:

Hint
: if any other codes besides p0128 is output, perform the troubleshooting for those dtcs first.


Replace ecm
Other materials:
Pre–check
1. Diagnosis system
Release the parking brake lever.
check the warning lights.
When the ignition switch is turned on, check that the abs
warning light and brake warning light goes on for 3 sec.
Hint:
when the parking brake is applied or the level of the brake
fluid is low, the ...
Adjustment
Hint:
in the rh side, work in the same procedure as in the lh side.
Since the centering bolt is used as a door side hinge bolt,
the door hinge cannot be adjusted with it on. Substitute
the bolt with washer for the centering bolt.
1. Inspect rear door panel sub–assy lh
Check ...
Circuit description
Refer to dtc p0120
Dtc no.
Dtc detection condition
Trouble area
P0121
The following condition is met 4 times. After the vehicle speed
has exceeded 19 mph (30 km/h) once, the throttle position
sensor output value is out of normal range when the throttle
...


