Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
The ECM estimates the ECT based on the starting temperature, engine loads, and engine speeds. The ECM then
compares the estimated temperature 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 interprets this as a
malfunction in the thermostat or the engine cooling system and sets the DTC.
MONITOR STRATEGY
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL ENABLING CONDITIONS
Related DTCs
P0128: Coolant Thermostat
Required Sensors/Components
(Main)
Thermostat
Required Sensors/Components
(Related)
Engine Coolant Temperature (ECT) sensor, Intake Air Temperature
(IAT) sensor, Vehicle speed sensor
Frequency of Operation
Once per driving cycle
Duration
900 seconds
MIL Operation
2 driving cycles
Sequence of Operation
None
Monitor runs whenever following
DTCs not present
P0010, P0020 (VVT Oil Control Valve)
P0011, P0021 (VVT System - Advance)
P0012, P0022 (VVT System - Retard)
P0016, P0018 (VVT System - Misalignment)
P0013, P0023 (Exhaust VVT Oil Control Valve)
P0014, P0024 (Exhaust VVT System - Advance)
P0015, P0025 (Exhaust VVT System - Retard)
P0017, P0019 (Exhaust VVT System - Misalignment)
P0031, P0032, P0051, P0052 (Air Fuel Ratio Sensor Heater)
P2195, P2196, P2197, P2198, P2237, P2238, P2239, P2240, P2241,
P2242, P2252, P2253, P2255, P2256, P2A00, P2A03 (Air Fuel Ratio
Sensor)
P0102, P0103 (Mass Air Flow Sensor)
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, P0174, P0175 (Fuel System)
P0301 - P0308 (Misfire)
P0335 (Crankshaft Position Sensor)
P1340 (Camshaft Position Sensor)
P0340, P0342, P0343, P0345, P0347, P0348 (VVT Sensor)
P0365, P0367, P0368, P0390, P0392, P0393 (Exhaust VVT Sensor)
P0351 - P0358 (Igniter)
2009 Toyota Tundra
2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra