DTC P0401: EGR Insufficient Flow Reset the ECM/PCM (see page 11-312). Test-drive under the following conditions. Without any electrical load. Decelerate from 88 km/h (55 mph) for at least 5 seconds. Check the Temporary DTC with scan tool. Is Temporary DTC P0401 indicated? YES - Clean the intake manifold EGR port with carburettor cleaner. Clean the passage inside the EGR valve with carburettor cleaner or replace the EGR valve. NO - Intermittent failure, go to step 4. Turn the ignition switch OFF. Disconnect the EGR valve 6P connector. Connect the battery positive terminal to EGR valve connector terminal No. 4. EGR VALVE 6P CONNECTOR Terminal side of male terminals Start the engine and let it idle, then connect the battery negative to terminal No. 6. Did the engine stall or run rough? YES - Intermittent failure, system is OK at this time. NO - Clean the intake manifold EGR port with carburettor cleaner. Clean the passage inside the EGR valve with carburettor cleaner or replace the EGR valve.

DTC P1491: EGR Valve Insufficient Lift Reset the ECM/PCM (see page 11-312). Start the engine. Hold the engine at 3,000 rpm (min-1) with no load (in Park or neutral) until the radiator fan comes on. Drive the vehicle under load for about 10 minutes. Try to keep the engine speed in the 1,700-2,500 rpm (min-1) range. Check the Temporary DTC with the scan tool. Is Temporary DTC P1491 indicated? YES - Go to step 5. NO - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the EGR valve and at the ECM/PCM. Turn the ignition switch OFF. Disconnect the EGR valve 6P connector. Start the engine and let it idle. Measure voltage between the EGR valve 6P connector terminals No. 4 and No. 6. EGR VALVE 6P CONNECTOR Wire side of female terminals Is there battery voltage? YES - Substitute a known-good ECM/PCM and recheck (see page 11-313). If symptom/indication goes away, replace the original ECM/PCM. NO - Go to step 9.