Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Exhaust Gas Recirculation "A" Low / Insufficient Flow (P04019C)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Engine / A25a-fxs Engine Control / Sfi System / Exhaust Gas Recirculation "A" Low / Insufficient Flow (P04019C)

DESCRIPTION

Based on the driving conditions, the ECM regulates the volume of exhaust gas that is recirculated to each engine cylinder in order to lower the combustion temperature and reduce NOx emissions. The ECM monitors signals such as engine speed, engine coolant temperature, electric load, and vehicle speed. When the EGR permission conditions are met, the ECM controls the opening of the EGR valve linearly through signals to the EGR step motor.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory	Note
P04019C	Exhaust Gas Recirculation "A" Low / Insufficient Flow	Change in intake manifold pressure is small when the EGR valve opened and closed during fuel cut operation (2 trip detection logic).	EGR valve assembly EGR passage EGR cooler assembly Intake system Manifold absolute pressure sensor	Comes on	DTC stored	SAE Code: P0401

MONITOR DESCRIPTION

The ECM monitors the pressure inside the intake manifold while opening and closing the EGR valve during fuel cut operation. If there is no change in the manifold absolute pressure sensor value, the ECM interprets this as a malfunction of the EGR valve assembly, illuminates the MIL and stores this DTC.

MONITOR STRATEGY

Related DTC	P0401: EGR valve high flow rate/low flow rate
Required Sensors/Components (Main)	EGR valve assembly Manifold absolute pressure sensor
Required Sensors/Components (Related)	Engine coolant temperature sensor
Frequency of Operation	Once per driving cycle
Duration	Within 5 seconds
MIL operation	2 driving cycles
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	P0010, P1360, P1362, P1364, P1366, P2614 (Motor drive VVT system control module) P0011 (VVT system - advance) P0012 (VVT system - retard) P0013 (Exhaust VVT oil control solenoid) P0014 (Exhaust VVT system - advance) P0015 (Exhaust VVT system - retard) P0016 (VVT system - misalignment) P0017 (Exhaust VVT system - misalignment) P0031, P0032, P101D (Air fuel ratio sensor (sensor 1) heater) P0101, P0102, P0103 (Mass air flow meter) P0106, P0107, P0108 (Manifold absolute pressure) P0111, P0112, P0113 (Intake air temperature sensor) P0116, P0117, P0118 (Engine coolant temperature sensor) P0121, P0122, P0123, P0222, P0223, P2135 (Throttle position sensor) P0125 (Insufficient coolant temperature for closed loop fuel control) P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air fuel ratio sensor (sensor 1)) P0171, P0172 (Fuel system) P0327, P0328 (Knock control sensor) P0335, P0337, P0338 (Crankshaft position sensor) P0340, P0342, P0343 (Camshaft position sensor) P0365, P0367, P0368 (Exhaust camshaft position sensor) P0489, P0490 (EGR control circuit) P0657, P2102, P2103, P2111, P2112, P2119 (Throttle actuator) P106A (Evaporative emission control system pressure sensor - manifold pressure sensor correlation) P11EA, P11EC, P11ED, P11EE, P11EF, P219A, P219C, P219D, P219E, P219F (Air-fuel ratio imbalance) P2228, P2229 (Atmospheric pressure sensor)
Time after engine started	3 seconds or more
Time after engine fuel cut	2597 msec or more
Engine speed	950 to 1600 rpm
Vehicle speed	20 km/h (13 mph) or more
Engine coolant temperature	75°C (167°F) or higher
Auxiliary battery voltage	11 V or higher
Intake air temperature	-10°C (14°F) or higher
Atmospheric pressure	76 kPa(abs) [11 psi(abs)] or higher

TYPICAL MALFUNCTION THRESHOLDS

Manifold pressure change	Less than 1.72 kPa [0.25 psi]
At engine speed	2400 rpm

MONITOR RESULT

Refer to detailed information in Checking Monitor Status.

Click here

P0401: Exhaust Gas Recirculation / VVT / EGR FLOW INSUFFICIENCY

Monitor ID	Test ID	Scaling	Unit	Description
$31	$BD	Multiply by 0.01	kPa	Delta manifold absolute pressure

CONFIRMATION DRIVING PATTERN

HINT:

After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
Click here
When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.
Click here

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG).
Turn the Techstream on.
Put the engine in Inspection Mode (Maintenance Mode).
Click here
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [A].
With the engine running, accelerate the vehicle to 65 km/h (40 mph) or more by depressing the accelerator pedal for at least 10 seconds [B].
CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

HINT:

When accelerating the vehicle, depress the accelerator pedal more than normal to start the engine.
Idle the engine for 30 seconds or more [C].
With the shift lever in S and the engine running, accelerate the vehicle to 65 km/h (40 mph) or more [D].
CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

HINT:

If the engine stops, further depress the accelerator pedal to restart the engine.
Perform the fuel cut operation for 5 seconds or more, with the accelerator pedal fully released [E].
Enter the following menus: Powertrain / Engine / Monitor / Current Monitor [F].
Check that Exhaust Gas Recirculation/VVT / Current is Complete.
HINT:

If the monitor item Exhaust Gas Recirculation/VVT / Current is Incomplete, perform the driving pattern again.
Enter the following menus: Powertrain / Engine / Monitor / Current Monitor / Exhaust Gas Recirculation/VVT / Details.
Check the Details (EGR FLOW INSUFFICIENCY).
HINT:

Make sure that the value is between MIN and MAX.
If the monitor item Exhaust Gas Recirculation/VVT / Current is still Incomplete, perform the following procedure.
Enter the following menus: Powertrain / Engine / Trouble Codes.
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 / Utility / All Readiness.
Input the DTC P04019C.

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

HINT:

If the judgment result is NORMAL, the system is normal.
If the judgment result is ABNORMAL, the system has a malfunction.
If the judgment result is INCOMPLETE, perform the steps [A] through [F] again.
[A] to [F]: Normal judgment procedure.
The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

WIRING DIAGRAM

Refer to DTC P040318.

Click here

CAUTION / NOTICE / HINT

NOTICE:

Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.
Click here

(Select Powertrain in Health Check and then check the time stamp data.)

Click here
If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.
Click here

HINT:

By using the Control the EGR Step Position Active Test, the operation of the EGR valve can be checked.

If the EGR valve is normal and is opened using the Active Test, the Data List value changes as follows.

Data List Item	Change in Data List when Number of Steps is Increased Using Control the EGR Step Position Active Test
Intake Manifold Absolute Pressure	Pressure rises

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

1.	CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P04019C)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

Powertrain > Engine > Trouble Codes

Result	Proceed to
DTC P04019C is output	A
DTC P04019C and other DTCs are output	B

HINT:

If any DTCs other than P04019C are output, troubleshoot those DTCs first.

GO TO DTC CHART

2.	READ VALUE USING TECHSTREAM (INTAKE MANIFOLD ABSOLUTE PRESSURE)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Enter the following menus: Powertrain / Engine / Data List / Intake Manifold Absolute Pressure.

Powertrain > Engine > Data List

Tester Display
Intake Manifold Absolute Pressure

(e) Read the value of Intake Manifold Absolute Pressure.

Standard:

Techstream Display	Specified Condition
Intake Manifold Absolute Pressure	80 to 110 kPa (11.6 to 15.95 psi)

REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

3.	PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Put the engine in Inspection Mode (Maintenance Mode).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

(e) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

HINT:

The A/C switch and all accessories should be off.

(f) Enter the following menus: Powertrain / Engine / Active Test / Control the EGR Step Position / Data List / Intake Manifold Absolute Pressure, Coolant Temperature and Engine Independent.

Powertrain > Engine > Active Test

Active Test Display
Control the EGR Step Position

Data List Display
Intake Manifold Absolute Pressure
Coolant Temperature
Engine Independent

(g) According to the display on the Techstream, compare the values of Data List item Intake Manifold Absolute Pressure before and while performing the Active Test.

NOTICE:

Make sure that the value of Data List item Engine Independent is "Operate" while performing the Active Test.
Do not leave the EGR valve open for 10 seconds or more during the Active Test.
Be sure to return the EGR valve to step 0 when the Active Test is completed.
Do not open the EGR valve 30 steps or more during the Active Test.

Standard:

The value of Intake Manifold Absolute Pressure changes according to the EGR valve step set by the Active Test.

Data List

Control the EGR Step Position (Active Test)

Before Active Test

(Engine idling)

0 Steps

0 to 30 Steps

(Engine idling)

Intake Manifold Absolute Pressure

20 to 40 kPa (2.9 to 5.8 psi)

(EGR valve is fully closed)

Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed

HINT:

If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

Result	Proceed to
Before performing the Active Test (while the engine is idling), the value of Intake Manifold Absolute Pressure is not between 20 to 40 kPa (2.9 to 5.8 psi).	A
When performing the Active Test to change the EGR valve step between 0 (EGR valve fully closed) and 30, the value of Intake Manifold Absolute Pressure changes less than 10 kPa (1.45 psi).	B
Other than above	C

GO TO STEP 6

GO TO STEP 12

4.	CHECK INTAKE SYSTEM

(a) Check the intake system for vacuum leaks.

Click here

OK:

No leaks from intake system.

HINT:

Perform "Inspection After Repair" after repairing or replacing the intake system.

Click here

REPAIR OR REPLACE INTAKE SYSTEM

5.	INSPECT EGR VALVE ASSEMBLY

(a) Remove the EGR valve assembly.

Click here

(b) Check if the EGR valve is stuck open.

OK:

EGR valve is tightly closed.

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly.

Click here

REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

REPLACE EGR VALVE ASSEMBLY

6.	REPLACE EGR VALVE ASSEMBLY

(a) Replace the EGR valve assembly.

Click here

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly.

Click here

CLEAR DTC

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Clear the DTCs.

Powertrain > Engine > Clear DTCs

(e) Turn the power switch off and wait for at least 30 seconds.

8.	CHECK WHETHER DTC OUTPUT RECURS (DTC P04019C)

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

Powertrain > Engine > Trouble Codes

Result	Proceed to
DTCs are not output	A
DTC P04019C is output	B

END

9.	REPLACE EGR COOLER ASSEMBLY

(a) Replace the EGR cooler assembly.

Click here

HINT:

If any of the EGR system related pipes (EGR pipe, exhaust manifold, etc.) are cracked, damaged or clogged, replace them as necessary.
Perform "Inspection After Repair" after replacing the EGR system.
Click here

10.

CLEAR DTC

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Clear the DTCs.

Powertrain > Engine > Clear DTCs

(e) Turn the power switch off and wait for at least 30 seconds.

11.	CHECK WHETHER DTC OUTPUT RECURS (DTC P04019C)

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

Powertrain > Engine > Trouble Codes

OK:

DTCs are not output.

END

12.

CLEAR DTC

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Clear the DTCs.

Powertrain > Engine > Clear DTCs

(e) Turn the power switch off and wait for at least 30 seconds.

13.	CHECK WHETHER DTC OUTPUT RECURS (DTC P04019C)

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

Powertrain > Engine > Trouble Codes

Result	Proceed to
DTCs are not output	A
DTC P04019C is output	B

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly.

Click here

END

REPLACE EGR VALVE ASSEMBLY

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