DTC 0302
EGR Function (DTC: 0302)
SYSTEM DESCRIPTION
This system cuts and controls vacuum applied to the EGR valve to suit engine operating conditions. This cut-and-control operation is accomplished through the ECM and the EGRC-solenoid valve. When the ECM detects any of the following conditions, current flows through the solenoid valve. This causes the port vacuum to be discharged into the atmosphere. The EGR valve remains closed.
- Low engine coolant temperature
- Engine starting
- Engine stopped
- Engine idling
- Excessively high engine coolant temperature
- Mass air flow sensor malfunction
- High engine speed
COMPONENT DESCRIPTION
Exhaust gas recirculation (EGR) valve
The EGR valve controls the amount of exhaust gas routed to the intake manifold. Vacuum is applied to the EGR valve in response to throttle valve opening. The vacuum controls the movement of a taper valve connected to the vacuum diaphragm in the EGR valve.
EGRC-solenoid valve
The EGRC-solenoid valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the coil in the solenoid valve is energized. A plunger will then move to cut the vacuum signal from the throttle body to the EGR valve.
When the ECM sends an OFF signal, the vacuum signal passes through the solenoid valve. The signal then reaches the EGR valve.
ON BOARD DIAGNOSIS LOGIC
If the absence of EGR flow is detected by EGR temperature sensor under the condition that calls for EGR, a low-flow malfunction is diagnosed.
If EGR temperature sensor detects EGR flow under the condition that does not call for EGR, a high-flow malfunction is diagnosed.
DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
OVERALL FUNCTION CHECK
Use this procedure to check the overall EGR function. During this check, a DTC might not be confirmed.
Before starting with the following procedure, check the engine coolant temperature of the freeze frame data with CONSULT or Generic Scan Tool.
If the engine coolant temperature is higher than or equal to 75°C (167°F), perform only "Procedure for malfunction A".
If the engine coolant temperature is lower than 75°C (167°F), perform both "Procedure for malfunction A" and "Procedure for malfunction B".
If the freeze frame data for another malfunction is stored in the ECM, perform both "Procedure for malfunction A" and "Procedure for malfunction B". In this case, check DTCs in the ECM and perform inspections one by one based on "INSPECTION PRIORITY".
Procedure for malfunction A
With Consult
1) Start engine and warm it up sufficiently.
2) Select "EGRC SOLENOID VALVE" in "ACTIVE TEST" mode with CONSULT and turn the solenoid valve "OFF".
3) Check the EGR valve lifting when revving engine from 3,000 rpm up to 4,000 rpm under no load.
(If necessary, check it using a suitable tool.)
EGR valve should lift up and down without sticking.
4) Check voltage between EGR temperature sensor harness connector terminal (1) and ground at idle speed.
Less than 4.5V should exist.
5) Turn ignition switch "OFF".
6) Check harness continuity between EGR temperature sensor harness connector terminal (2) and ECM terminal (43).
Continuity should exist.
7) Perform "COMPONENT CHECK", "EGR temperature sensor".
OR
Without Scan Tools
1) Disconnect EGRC-solenoid valve harness connector.
(The DTC for EGRC-solenoid valve will be displayed, however, ignore it.)
2) Start engine and warm it up sufficiently.
3) Check the EGR valve lifting when revving engine from 3,000 rpm up to 4,000 rpm under no load.
(If necessary, check it using with a suitable tool.)
EGR valve should lift up and down without sticking.
4) Reconnect EGRC-solenoid valve harness connector.
5) Check voltage between EGR temperature sensor harness connector terminal (1) and ground at idle speed.
Less than 4.5V should exist.
6) Turn ignition switch "OFF".
7) Check harness continuity between EGR temperature sensor harness connector terminal (2) and ECM terminal (43).
Continuity should exist.
8) Perform "COMPONENT CHECK", "EGR temperature sensor".
Procedure for malfunction B
With Consult
1) Start engine.
2) Select "EGRC SOLENOID VALVE" in "ACTIVE TEST" mode with CONSULT and turn the solenoid valve "ON".
3) Check for the EGR valve lifting when revving engine from 3,000 rpm up to 4,000 rpm under no load. (If necessary, check it using a suitable tool.)
EGR valve should be closed and should not lift up.
OR
With GST
1) Turn ignition switch "ON".
2) Confirm the engine coolant temperature is lower than 55°C (131°F) in "Mode 1" with GST.
Perform the following steps before its temperature becomes higher than 55°C (131°F).
3) Start engine.
4) Check for the EGR valve lifting when revving engine from 3,000 rpm up to 4,000 rpm under no load. (If necessary, check it using a suitable tool.)
EGR valve should be closed and should not lift up.
OR
Without Scan Tools
1) Turn ignition switch "ON".
2) Confirm the voltage between ECM terminals (59) and (25) is higher than 2.1 V.
Perform the following steps before the voltage becomes lower than 2.1 V.
3) Start engine.
4) Check for the EGR valve lifting when revving engine from 3,000 rpm up to 4,000 rpm under no load. (If necessary, check it using a suitable tool.)
EGR valve should be closed and should not lift up.
WIRING DIAGRAM
DIAGNOSTIC PROCEDURE
COMPONENT INSPECTION
EGR valve
Apply vacuum to EGR valve vacuum port with a hand vacuum pump.
EGR valve spring should lift.
If NG, replace EGR valve.
EGRC-solenoid valve
Check solenoid valve, following the table as shown:
If NG, replace the solenoid valve.
EGR temperature sensor
Check resistance as shown in the figure.
(Reference data)
If NG, replace EGR temperature sensor.