Engine Hybrid System. Yaris. Ncp93, 131
1Nz-Fe Engine Control. Yaris. Ncp93, 131
TYPICAL MALFUNCTION THRESHOLDS
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0128)
DTC P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) |
DESCRIPTION
- HINT:
- This DTC relates to the thermostat.
| DTC No. | DTC Detection Condition | Trouble Area |
| P0128 |
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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 | 550 seconds |
| MIL Operation | 2 driving cycles |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| Monitor runs whenever following DTCs not present | P0010 (Camshaft Timing Oil Control Valve) P0011 (VVT System - Advance) P0012 (VVT System - Retard) P0016 (VVT System - Misalignment) P0031, P0032, P0101D (Air Fuel Ratio Sensor Heater) P2195, P2196, P2237, P2238, P2239, P2252, P2253, P014C, P014D, P015A, P015B (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 (Fuel System) P0301 - P0304 (Misfire) P0335 (Crankshaft Position Sensor) P0340 (Camshaft Position Sensor) P0351 - P0354 (Igniter) P0500 (Vehicle Speed Sensor) |
| Battery voltage | 11 V or higher |
| Either of following conditions met: | 1 or 2 |
| 1. All of following conditions met: | - |
| -15 to 7°C (-27 to 12.6°F) |
| -10 to 56°C (14 to 133°F) |
| -10 to 56°C (14 to 133°F) |
| 2. All of following conditions met: | - |
| Higher than 7°C (12.6°F) |
| 56°C (133°F) or less |
| -10°C (14°F) or higher |
| Accumulated time at vehicle speed of 80 mph (128 km/h) 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
- Stop the engine and allow it to soak.
- Connect the Techstream to the DLC3.
- Turn the ignition switch to ON and turn the Techstream on [A].
- Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp and Intake Air.
- Check that "Coolant Temp" is 56°C (133°F) or less and "Intake Air" is between 0 and 35°C (32 and 95°F).
- Set the heater 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) for 10 minutes [B].
- NOTICE:
- When performing the confirmation driving pattern, obey all speed limits and traffic laws.
- HINT:
- Data can be captured relatively easily by using the snapshot function in the Data List.
- Enter the following menus: Data List / Function / Snap shot configuration / Record time / 5 min.
- Data capture can be started by using the target point function. For example, setting the target point to an engine speed of 4000 rpm and then racing the engine, etc. to raise the engine speed to a speed of 4000 rpm or more will cause data capture to start.
- After "Coolant Temp" stabilizes, check that "Coolant Temp" is 75°C (167°F) or higher [C].
- HINT:
- If "Coolant Temp" is below 75°C (167°F) while driving the vehicle at 80 km/h (50 mph), inspect the cooling system and thermostat.
INSPECTION PROCEDURE
- HINT:
- 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.
- 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.
| 1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0128) |
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Read DTCs.
Result 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.
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| A | |
| 2.CHECK COOLING SYSTEM |
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.
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| OK | |
| 3.INSPECT THERMOSTAT |
Inspect the thermostat (YARIS_NCP93 RM000001DG801EX.html).
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| OK | ||
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