- Less than 0.005°C/sec (0.009°F/sec) (for CVT models)
- Less than -0.025°C/sec (-0.045°F/sec) (for Manual Transaxle models)
| Last Modified: 05-13-2024 | 6.11:8.1.0 | Doc ID: RM100000001HT33 |
| Model Year Start: 2020 | Model: Corolla | Prod Date Range: [03/2019 - 11/2022] |
| Title: 2ZR-FAE (ENGINE CONTROL): SFI SYSTEM: P0128; Thermostat; 2020 - 2023 MY Corolla [03/2019 - 11/2022] | ||
|
DTC |
P0128 |
Thermostat |
DESCRIPTION
The ECM uses the engine coolant temperature sensor, installed to the water outlet, to monitor the operation of the thermostat.
|
DTC No. |
Detection Item |
DTC Detection Condition |
Trouble Area |
MIL |
Memory |
Note |
|---|---|---|---|---|---|---|
|
P0128 |
Thermostat |
Either of the following conditions is met (2 trip detection logic):
|
|
Comes on |
DTC stored |
DTC for Mexico Models - Does not apply |
MONITOR DESCRIPTION
Judgment by Simulated Engine Coolant Temperature
The ECM estimates the engine coolant temperature based on the starting temperature, engine loads, and engine speeds. The ECM then compares the estimated temperature with the actual engine coolant temperature. When the estimated engine coolant temperature reaches 73°C (163°F),, the ECM checks the actual engine coolant temperature. If the actual engine coolant temperature is less than 73°C (163°F), the ECM interprets this as a malfunction in the thermostat or the engine cooling system and stores the DTC.
Judgment by Engine Coolant Temperature Change at High Vehicle Speed
When the vehicle is being driven between 65 and 128 km/h (40.625 and 80 mph) and the monitoring conditions are met, the change in engine coolant temperature is monitored. The amount of change is judged to be normal or abnormal every 15 seconds, in order to monitor the thermostat operation. If the engine coolant temperature changes more than the threshold, the thermostat is judged as normal, but if it changes less than the threshold, the thermostat is judged to be malfunctioning. If an abnormal judgment is made 3 times, the ECM will illuminate the MIL and store a DTC.
MONITOR STRATEGY
|
Related DTCs |
P0128: Coolant thermostat (jugement by simulated engine coolant temperature) P0128: Coolant thermostat (jugement by engine coolant temperature change at high vehicle speed) |
|
Required Sensors/Components (Main) |
Thermostat Engine coolant temperature sensor |
|
Required Sensors/Components (Related) |
Intake air temperature sensor Vehicle speed sensor |
|
Frequency of Operation |
Once per driving cycle: Judgment by simulated engine coolant temperature Continuous: Judgment by engine coolant temperature change at high vehicle speed |
|
Duration |
280 seconds: Judgment by simulated engine coolant temperature -: Judgment by engine coolant temperature change at high vehicle speed |
|
MIL Operation |
2 driving cycles |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
ALL
|
Monitor runs whenever the following DTCs are not stored |
P0010 (Camshaft timing oil control valve) P0011 (VVT system - advance) P0012 (VVT system - retard) P0013 (Exhaust camshaft timing oil control valve) P0014 (Exhaust VVT system - advance) P0015 (Exhaust VVT system - retard) P0016 (VVT system - misalignment) P0017 (Exhaust VVT system - misalignment) P0031, P0032 (Air fuel ratio sensor heater) P0102, P0103 (Mass air flow meter) P0107, P0108 (Manifold absolute pressure) P0112, P0113 (Intake air temperature sensor) P0115, P0117, P0118 (Engine coolant temperature sensor) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle position sensor) P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air fuel ratio sensor) P0171, P0172 (Fuel system) P0300, P0301, P0302, P0303, P0304 (Misfire) P0335 (Crank position sensor) P0340, P0342, P0343 (Cam position sensor) P0365, P0367, P0368, (Exhaust cam position sensor) P0500 (Vehicle speed sensor) P219A, P219C, P219D, P219E, P219F (Air-fuel ratio imbalance) |
Judgment by Simulated Engine Coolant Temperature
|
Battery voltage |
11 V or higher |
|
Either of the following conditions is met |
1 or 2 |
|
1. All of the following conditions are met |
(a), (b) and (c) |
|
(a). Engine coolant temperature at engine start - Intake air temperature at engine start |
-15 to 7°C (-27 to 12.6°F) |
|
(b). Engine coolant temperature at engine start |
-10 to 56°C (14 to 133°F) |
|
(c). Intake air temperature at engine start |
-10 to 56°C (14 to 133°F) |
|
2. All of the following conditions are met |
(d), (e) and (f) |
|
(d). Engine coolant temperature at engine start - Intake air temperature at engine start |
Higher than 7°C (12.6°F) |
|
(e). Engine coolant temperature at engine start |
56°C (133°F) or less |
|
(f). Intake air temperature at engine start |
-10°C (14°F) or higher |
|
Accumulated time that vehicle speed is 128 km/h (80 mph) or more |
Less than 20 seconds |
Judgment by Engine Coolant Temperature Change at High Vehicle Speed
|
During that all of the following conditions are met |
15 seconds or more |
|
Battery voltage |
11 V or higher |
|
Engine coolant temperature at engine start |
-10°C (14°F) or higher |
|
Intake air temperature at engine start |
-10°C (14°F) or higher |
|
Engine speed |
0 to 4500 rpm |
|
Vehicle speed |
65 to 128 km/h (40.625 to 80 mph) |
TYPICAL MALFUNCTION THRESHOLDS
Judgment by Simulated Engine Coolant Temperature
|
Duration that both of the following conditions are met |
5 seconds or more |
|
Estimated engine coolant temperature |
73°C (163°F) or higher |
|
Engine coolant temperature sensor output |
Less than 73°C (163°F) |
Judgment by Engine Coolant Temperature Change at High Vehicle Speed
|
Malfunction counter |
3 times or more |
|
Malfunction counter is incremented when following conditions are met |
A and B |
|
A. Average engine coolant temperature change (vary with current engine coolant temperature, estimated ambient air temperature, intake air mass and vehicle speed) |
|
|
B. Engine coolant temperature is satisfied throughout this period |
Less than 73°C (163°F) |
CONFIRMATION DRIVING PATTERN
- Stop the engine and allow it to soak.
- Connect the Techstream to the DLC3.
- Turn the ignition switch to ON [A].
- Turn the Techstream on.
- Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp and Intake Air.
- Check that the value of the Data List item Coolant Temp is 56°C (133°F) or less and the value of the Data List item Intake Air Temperature is between 0 and 35°C (32 and 95°F).
- Set the heater control to MAX HOT with fresh air mode selected and turn the A/C off.
-
Start the engine and drive the vehicle at 80 km/h (50 mph) or more for 20 minutes [B].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
-
After the value of the Data List item Coolant Temperature stabilizes, check that it is 73°C (163°F) or higher.
HINT:
If the value of the Data List item Coolant Temperature is less than 73°C (163°F) while driving the vehicle at 80 km/h (50 mph), inspect the cooling system and thermostat.
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
-
Read the pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
- Input the DTC: P0128.
-
Check the DTC judgment result.
Techstream Display
Description
NORMAL
- DTC judgment completed
- System normal
ABNORMAL
- DTC judgment completed
- System abnormal
INCOMPLETE
- DTC judgment not completed
- Perform driving pattern after confirming DTC enabling conditions
N/A
- Unable to perform DTC judgment
- Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
HINT:
- If the judgment result is NORMAL, the system is normal.
- If the judgment result is ABNORMAL, the system has a malfunction.
- If the judgment result is INCOMPLETE or N/A, If the judgment result is INCOMPLETE, perform steps [D] through [G].
- With the engine stopped, leave the vehicle outside overnight [D].
- Turn the ignition switch to ON [E].
- Turn the Techstream on.
- Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.
- Check that the value of the Data List item Coolant Temp is 25°C (77°F) or less.
-
Start the engine and drive the vehicle at 90 km/h (56 mph) or more for 20 minutes [F].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [G].
-
Read the pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
- Input the DTC: P0128.
-
Check the DTC judgment result again.
Techstream Display
Description
NORMAL
- DTC judgment completed
- System normal
ABNORMAL
- DTC judgment completed
- System abnormal
INCOMPLETE
- DTC judgment not completed
- Perform driving pattern after confirming DTC enabling conditions
N/A
- Unable to perform DTC judgment
- Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
HINT:
- If the judgment result is NORMAL, the system is normal.
- If the judgment result is ABNORMAL, the system has a malfunction.
-
If the judgment result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs.
Click here
![2020 - 2022 MY Corolla [03/2019 - 09/2022]; 2ZR-FAE (ENGINE CONTROL): SFI SYSTEM: DTC CHECK / CLEAR](/t3Portal/stylegraphics/info.gif)
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
CAUTION / NOTICE / HINT
HINT:
- When the DTC is output, check the engine coolant temperature using the Techstream. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp. If the Coolant Temp value is lower than the actual engine coolant temperature, the engine coolant temperature sensor circuit may be malfunctioning. In this case, check the wire harnesses and connectors (and those connections) between the ECM and the engine coolant temperature sensor first.
- Read Freeze Frame Data using the Techstream. The ECM records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. 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.
PROCEDURE
|
1. |
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0128) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read the DTCs.
Powertrain > Engine and ECT > Trouble Codes
|
Result |
Proceed to |
|---|---|
|
DTC P0128 is output |
A |
|
DTC P0128 and other DTCs are output |
B |
HINT:
If any DTCs other than P0128 are output, troubleshoot those DTCs first.
| B |
|
GO TO DTC CHART
|
|
|
2. |
CHECK COOLING SYSTEM |
(a) Check for defects in the engine cooling system that might cause the system to be too cold, such as abnormal cooling fan operation or any modifications.
| NG |
|
REPAIR OR REPLACE COOLING SYSTEM |
|
|
3. |
INSPECT THERMOSTAT |
(a) Inspect the thermostat (thermostat opening temperature).
Click here
| NG |
|
|
|
4. |
INSPECT ENGINE COOLANT TEMPERATURE SENSOR |
(a) Inspect the engine coolant temperature sensor.
Click here
HINT:
Perform "Inspection After Repair" after replacing the engine coolant temperature sensor.
Click here
| OK |
|
REPLACE ECM
|
| NG |
|
REPLACE ENGINE COOLANT TEMPERATURE SENSOR
|
|
|