System Check
- With engine cold, disconnect vacuum hose from EGR valve at manifold and connect vacuum gauge to hose. Start engine and slowly raise to 4500 RPM. No vacuum should be shown on gauge.
- If vacuum is present, check for voltage at EGR control solenoid valve A (Blue/Yellow wire at emission control box connector on Accord models or Blue wire at box #2 on Civic and Prelude models).
- If voltage is present, replace EGR control solenoid valve A (on left side of front row of emission control box on Accord models or on box #2 on Civic and Prelude models) and retest. If no voltage, check wiring, fuse and thermosensor.
- Disconnect vacuum hose from EGR valve and connect vacuum gauge to hose. Push positive probe of voltmeter into Blue/Yellow terminal at the control box connector on Accord models or into Blue terminal at control box #2 on Civic and Prelude models. Put negative probe to ground.
- Raise front of vehicle and support with safety stands. Start engine and warm to normal operating temperature (cooling fan on). Vacuum and voltage should match specifications given in "EGR System Test" chart.
- If all readings are correct, check EGR valve for proper operation. If vacuum of more than 2 in. (51 mm) Hg. is noted (but no voltage) replace EGR control valve and check vacuum hose routing. If any other readings are not correct, perform all other tests in sequence.EGR SYSTEM TEST
Condition of Engine EGR Valve Vacuum Blue/White Wire Voltage Idle None None 4500 RPM Yes None 4500 RPM (Blocked EGR Bleed) (1) Less Than 2 in. Hg None Hard Acceleration over 15 MPH (2) Yes None Deceleration over 15 Mph 2 None Yes (1) See Figure. (2) In second gear or "2".