EGR System Check (1.0L)
- With engine cool, ensure EGR valve is not loose or broken. Replace as necessary. Start engine and warm to normal operating temperature. Place finger on bottom of EGR valve diaphragm. Increase engine speed. EGR valve diaphragm should move. If diaphragm does not move, go to next step.
- Allow engine to idle. Disconnect vacuum hose from EGR valve. See Fig 1. Apply 8 in. Hg (27 kPa) of vacuum to EGR valve and place finger on diaphragm. Vacuum should hold, diaphragm should move and engine should run rough and may stall. If EGR valve operation is not as specified, replace EGR valve. If EGR valve operation is as specified, go to next step.
- Check for carbon in valve which may cause a restriction. Restriction may be small enough so that engine may not stall, but large enough to cause DTC P0400 to set. See appropriate SELF-DIAGNOSTICS article. If EGR valve is plugged, replace EGR valve. If EGR valve is okay, see EGR PRESSURE TRANSDUCER (1.0L) .
Courtesy of GENERAL MOTORS CORP.