P011B
1UR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P011B: Engine Coolant Temperature / Intake Air Temperature Correlation
P011B - Engine Coolant Temperature / Intake Air Temperature Correlation
DESCRIPTION
The engine has two temperature sensors, an Engine Coolant Temperature (ECT) sensor and an Intake Air Temperature (IAT) sensor, to detect temperature while the engine is in operation. A thermistor, whose resistance value varies according to temperature, is built into each sensor. When the temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes. Based on these temperature signals output from the sensors, the ECM determines the fuel injection time and the ignition timing to control the engine.
HINT
- Waiting is required to prevent the temperature of the engine from affecting the readings. If the engine has been operated recently, it will not be possible to accurately compare the readings.
- For diagnosis, in order to duplicate the detection conditions of the DTC, it is necessary to park the vehicle for 7 hours. Parking the vehicle for 7 hours ensures that the actual temperature of the ECT and IAT are very similar. When the vehicle has been parked for less than 7 hours, differences in the readings may exist. However, this does not necessarily indicate a fault.
MONITOR DESCRIPTION
The ECM monitors the difference between the Engine Coolant Temperature (ECT) and the Intake Air Temperature (IAT) when the engine is started cold to detect the engine temperature conditions accurately. The monitor runs when the engine is started cold after 7 hours or more have elapsed since the engine was stopped (ignition switch turned off) on the previous trip. If the difference between the ECT and the IAT on a cold start exceeds 20°C (36°F), the ECM interprets this as a malfunction in the ECT and/or IAT sensor circuit, and stores the DTC.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
CONFIRMATION DRIVING PATTERN
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation) [A].
4. Turn the ignition switch off.
5. With the engine stopped, leave the vehicle as is for 7.5 hours or more [B].
6. Start the engine and wait 60 seconds or more [C].
7. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
8. 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.
9. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
10. Input the DTC: P011B.
11. Check the DTC judgment result.
HINT
If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [A] through [D] again.
12. If no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
INSPECTION PROCEDURE
PROCEDURE
1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P011B)
(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 DTCs.
Result:
HINT
If any DTCs other than P011B are output, troubleshoot those DTCs first.
B -- GO TO DTC CHART Engine Control System - SFI System
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (INTAKE AIR TEMPERATURE)
(a) Leave the vehicle for 7 hours or more.
HINT
It is necessary leave the vehicle for 7 hours or more to create conditions similar to the DTC detection conditions.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to ON.
(d) Turn the Techstream on.
(e) Enter the following menus: Powertrain / Engine and ECT / All Data / Intake Air.
(f) Read the value displayed on the Techstream.
OK:
Difference between the intake air temperature and the actual outside air temperature is within 10°C (18°F).
HINT
Temperature readings on the vehicle outside temperature gauge (if equipped) are not suitable for comparison with the IAT reading. The outside temperature gauge has a significant delay built-in to prevent temperature swings from being displayed on its display. Use an accurate thermometer to determine the outside air temperature.
NG -- REPLACE MASS AIR FLOW METER Removal
OK -- Continue to next step.
3. READ VALUE USING TECHSTREAM (COOLANT TEMPERATURE)
(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 / All Data / Coolant Temp.
(e) Read the value displayed on the Techstream.
OK:
The difference between the coolant temperature and the actual outside air temperature is within 10°C (18°F).
HINT
If the result is not as specified, check if there are heat sources such as a block heater in the engine compartment.
NG -- REPLACE ENGINE COOLANT TEMPERATURE SENSOR Removal
OK -- REPLACE ECM Removal