Exhaust Gas Recirculation: Testing and Inspection

SYSTEM OPERATION

EGR System Operation:

1. Connect Mazda SST (Engine Signal Monitor Adapter Harness), or equivalent test equipment.
2. Start engine. Accelerate engine and verify battery voltage at ECU terminal 4O while engine is cold.
3. Warm engine to operating temperature and run at idle.
4. Short ECU terminal 4O and verify that engine runs rough or stalls.

EGR VALVE CHECK

EGR Valve And Switch Inspection:

1. With valve removed, connect vacuum pump.
2. Check that valve moves when specified vacuum is applied.

VACUUM: 3.3 - 4.5 inHg (85 - 115 mmHg, 11.0 - 15.3 kPa)

3. If not as specified, replace EGR valve assembly.

EGR SWITCH CHECK (CALIF. ONLY)

1. Remove valve and connect vacuum pump.
2. Connect ohmmeter across switch terminals and apply vacuum. Switch should show continuity above the specified vacuum.

VACUUM: 3.3 - 4.5 inHg (85 - 115 mmHg, 11.0 - 15.3 kPa)

3. If not as specified, replace EGR valve assembly.

SOLENOID VALVE CHECK

Solenoid Valve Testing: