2ZR-FAE (ENGINE CONTROL): SFI SYSTEM: P011B; Engine Coolant Temperature / Intake Air Temperature Correlation; 2020 - 2023 MY Corolla [03/2019

The engine has two temperature sensors, an engine coolant temperature sensor and an intake air temperature sensor, to detect temperature while the engine is operating. A thermistor, whose resistance value varies according to the temperature, is built into each sensor. When the temperature becomes low, the resistance of the thermistor increases. When the temperature becomes 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 duration and the ignition timing to control the engine.

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 and intake air temperature are very similar. When the vehicle has been parked for less than 7 hours, differences in the readings may exist, but 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 accurately detect the engine temperature conditions. The monitor runs when the engine is started 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 engine coolant temperature and the intake air temperature on a cold start exceeds 25°C (45°F), the ECM interprets this as a malfunction in the engine coolant temperature sensor circuit and intake air temperature sensor circuit, and stores this DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the ignition switch to ON [A].
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off.
With the engine stopped, leave the vehicle as is for 7.5 hours or more [B].
Turn the ignition switch to ON.
Turn the Techstream on.
Start the engine and wait 60 seconds or more [C].
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
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.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P011B.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [A] through [D] again.

If no pending DTC is output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

CAUTION / NOTICE / 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.

PROCEDURE

Powertrain > Engine and ECT > Trouble Codes

It is necessary to leave the vehicle for 7 hours or more to create conditions similar to the DTC detection conditions.

(e) Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

Powertrain > Engine and ECT > Data List

Difference between the intake air temperature and the actual outside air temperature is within 10°C (18°F).

HINT:

Temperature readings on the outside temperature gauge of the vehicle (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 swings in the temperature display. Use an accurate thermometer to determine the outside air temperature.
Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly.
Click here

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.

Powertrain > Engine and ECT > Data List

The difference between the coolant temperature and the actual outside air temperature is within 10°C (18°F).