DTC    P0403    Exhaust Gas Recirculation Control Circuit

for Preparation Click here


DESCRIPTION

The ECM lowers combustion chamber temperatures and reduces Nitrogen Oxide (NOx) emissions by recirculating an appropriate amount of exhaust gas to the combustion chambers according to the engine operating conditions. When all EGR activation conditions are met (based on sensor signals such as engine speed, coolant temperature, load signal, vehicle speed signal), the ECM turns on the stepper motor inside the EGR valve and linearly controls the opening angle of the EGR valve. When the ECM determines that EGR operation will not influence engine operating conditions, the ECM forcibly opens and closes the EGR valve to monitor changes in manifold pressure. If the manifold pressure change is less than that during normal EGR valve operation, the ECM will detect a shortage of EGR gas flow and set a DTC. Also, an EGR DTC is set if a malfunction (open or short circuit) occurs in the EGR valve operation circuit.

DTC No.
DTC Detection Condition
Trouble Area
P0403
Both of the following conditions are met for 1 second or more
(1 trip detection logic):
  1. (a) The engine is running.
  2. (b) When any of terminals EGR1 to 4 has a fixed voltage of 0 V.
  1. Open or short in EGR circuit
  2. EGR valve assembly
  3. ECM

WIRING DIAGRAM


A187731E01


INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT:
Read freeze frame data using the intelligent tester. 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.

1.INSPECT EGR VALVE ASSEMBLY


    A157569E03

  1. Disconnect the EGR valve assembly connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    5 - 6
    		20°C (68°F)
    		18 to 22 Ω
    5 - 4
    		20°C (68°F)
    		18 to 22 Ω
    2 - 1
    		20°C (68°F)
    		18 to 22 Ω
    2 - 3
    		20°C (68°F)
    		18 to 22 Ω

    Text in Illustration 
    *1
    		Component without harness connected
    (EGR Valve Assembly)

  1. Reconnect the EGR valve assembly connector.



NG
REPLACE EGR VALVE ASSEMBLY (Click here)
OK


2.INSPECT EGR VALVE ASSEMBLY (POWER SOURCE VOLTAGE)


    A209303E02

  1. Disconnect the EGR valve assembly connector.

  1. Turn the ignition switch to ON.

  1. Measure the voltage according to the value(s) in the table below.

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    B49-2 (+B1) - Body ground
    		Ignition switch ON
    		11 to 14 V
    B49-5 (+B2) - Body ground
    		Ignition switch ON
    		11 to 14 V

    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to EGR Valve Assembly)

  1. Reconnect the EGR valve assembly connector.



NG
Go to step 4
OK


3.CHECK HARNESS AND CONNECTOR (EGR VALVE - ECM)

  1. Disconnect the EGR valve assembly connector.

  1. Disconnect the ECM connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance (Check for Open):
    Tester Connection
    		Condition
    		Specified Condition
    B49-6 (EGR1) - B8-50 (EGR1)
    		Always
    		Below 1 Ω
    B49-1 (EGR2) - B8-49 (EGR2)
    		Always
    		Below 1 Ω
    B49-4 (EGR3) - B8-48 (EGR3)
    		Always
    		Below 1 Ω
    B49-3 (EGR4) - B8-47 (EGR4)
    		Always
    		Below 1 Ω

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    B49-6 (EGR1) or B8-50 (EGR1) - Body ground
    		Always
    		10 kΩ or higher
    B49-1 (EGR2) or B8-49 (EGR2) - Body ground
    		Always
    		10 kΩ or higher
    B49-4 (EGR3) or B8-48 (EGR3) - Body ground
    		Always
    		10 kΩ or higher
    B49-3 (EGR4) or B8-47 (EGR4) - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the EGR valve assembly connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM (Click here)  

4.CHECK HARNESS AND CONNECTOR (EGR VALVE - INTEGRATION RELAY)

  1. Disconnect the EGR valve assembly connector.

  1. Remove the integration relay.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance (Check for Open):
    Tester Connection
    		Condition
    		Specified Condition
    B49-2 (+B1) - 1F-10
    		Always
    		Below 1 Ω
    B49-5 (+B2) - 1F-11
    		Always
    		Below 1 Ω

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    B49-2 (+B1) or 1F-10 - Body ground
    		Always
    		10 kΩ or higher
    B49-5 (+B2) or 1F-11 - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the EGR valve assembly connector.

  1. Reinstall the integration relay.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT (Click here)