DESCRIPTION
HINT:
This DTC relates to the thermostat.
This DTC is stored when the engine coolant temperature does not reach 75°C (167°F) despite sufficient engine warm-up time having elapsed.
DTC No. |
DTC Detection Condition |
Trouble Area |
---|---|---|
P0128 |
|
|
MONITOR DESCRIPTION
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 75°C (167°F), the ECM checks the actual engine coolant temperature. If the actual engine coolant temperature is less than 75°C (167°F), the ECM interprets this as a malfunction in the thermostat or the engine cooling system and stores the DTC.
MONITOR STRATEGY
Related DTCs |
P0128: Coolant Thermostat |
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 |
Duration |
510 seconds |
MIL Operation |
2 driving cycles |
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
Monitor runs whenever following DTCs not stored |
P0010 (Camshaft Timing Oil Control Valve) P0011 (VVT System - Advance) P0012 (VVT System - Retard) P0016 (VVT System - Misalignment) P0013 (Exhaust Camshaft Timing Oil Control Valve) P0014 (Exhaust VVT System - Advance) P0015 (Exhaust VVT System - Retard) P0017 (Exhaust VVT System - Misalignment) P0031, P0032, P101D (Air Fuel Ratio Sensor Heater) P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air Fuel Ratio Sensor) P0102, P0103 (Mass Air Flow Meter) P0112, P0113 (Intake Air Temperature Sensor) P0115, P0117, P0118 (Engine Coolant Temperature Sensor) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle Position Sensor) P0171, P0172 (Fuel System) P0300 - P0304 (Misfire) P0335 (Crankshaft Position Sensor) P0340, P0342, P0343 (Camshaft Position Sensor) P0365, P0367, P0368 (Exhaust Camshaft Position Sensor) P0351 - P0354 (Igniter) P0500 (Vehicle Speed Sensor) P219A, P219C, P219D, P219E, P219F (Air Fuel Ratio Imbalance) |
Battery voltage |
11 V or higher |
Either of following conditions 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 |
-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: |
(a), (b) and (c) |
(a) Engine coolant temperature at engine start - Intake air temperature at engine start |
Higher than 7°C (12.6°F) |
(b) Engine coolant temperature at engine start |
56°C (133°F) or less |
(c) Intake air temperature at engine start |
-10°C (14°F) or higher |
Accumulated time at vehicle speed of 128 km/h (80 mph) or more |
Less than 20 seconds |
TYPICAL MALFUNCTION THRESHOLDS
Duration that both of following conditions met |
5 seconds or more |
(a) Estimated engine coolant temperature |
75°C (167°F) or higher |
(b) Engine coolant temperature sensor output |
Below 75°C (167°F) |
CONFIRMATION DRIVING PATTERN
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT:
HINT:
If "Coolant Temp" is less than 75°C (167°F) while driving the vehicle at 80 km/h (50 mph), inspect the cooling system and thermostat.
CAUTION / NOTICE / HINT
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 / Trouble Codes.
(e) Read the DTCs.
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 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 (See page ).
NG | ![]() |
REPLACE THERMOSTAT |
|
4. |
INSPECT ENGINE COOLANT TEMPERATURE SENSOR |
(a) Inspect the engine coolant temperature sensor (See page
).
HINT:
Perform "Inspection After Repair" after replacing the engine coolant temperature
sensor (See page ).
OK | ![]() |
REPLACE ECM |
NG | ![]() |
REPLACE ENGINE COOLANT TEMPERATURE SENSOR |
Disposal
DISPOSAL
CAUTION / NOTICE / HINT
HINT:
The tire pressure warning valve and transmitter is powered by a lithium battery.
When disposing of the tire pressure warning valve and transmitter, remove the battery
and dispose of it correctly.
PROCEDURE
1. DIS ...
On-vehicle Inspection
ON-VEHICLE INSPECTION
PROCEDURE
1. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET
HINT:
This is a method where a manifold gauge set is used to help locate the problem.
(a) Read the manifold gauge pressure when the following conditions are met:
Test ...
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DESCRIPTION
The key reminder warning buzzer sounds when the driver side door is opened while
the ignition switch is in LOCK or ACC. The key reminder warning buzzer is activated
when the main body ECU (driver side junction block assembly) sends an unlock w ...