P011B

2AZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P011B: Engine Coolant Temperature / Intake Air Temperature Correlation

DTC P011B - Engine Coolant Temperature / Intake Air Temperature Correlation

DESCRIPTION

The engine has two temperature sensors, an engine coolant temperature sensor and an intake air temperature sensor, to detect the temperature while the engine is operating. A thermistor, whose resistance value varies according to the temperature, is built into each sensor. When the temperature is low, the resistance of the thermistor is high. When the temperature is high, the resistance is low. 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 duration 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 engine coolant temperature sensor and intake air temperature sensor are very similar. When the vehicle has been parked for less than 7 hours, differences in the readings may exist, this does not necessarily indicate a fault.

MONITOR DESCRIPTION

The ECM monitors the difference between the engine coolant temperature and the intake air temperature 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 has elapsed since the engine was stopped (ignition switch turned to off) on the previous trip. If the difference between the engine coolant temperature and the intake air temperature on a cold start exceeds 20°C (68°F), the ECM interprets this as a malfunction in the engine coolant temperature sensor circuit and intake air temperature sensor circuit, and sets the DTC.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





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 the ON position.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read the DTCs.
Result:





HINT: If any DTCs other than P011B are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART
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 to leave the vehicle for 7 hours or more to allow 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 / 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 (50°F).
HINT: Temperature readings on the vehicle outside temperature gauge (if equipped) are not suitable for comparing to the intake air temperature 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
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 (50°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
OK -- REPLACE ECM