MBE 900 DDEC VI Troubleshooting – Section 98.4 SPN 2791/FMI 7

Section 98.4
SPN 2791/FMI 7

This diagnosis typically means the EGR valve position is incorrect.‪

Section 98.4.1
EGR Valve Position Check

Check as follows:‪

1. Turn the ignition ON (key ON, engine OFF).
2. Using DDDL 7.0, monitor the EGR actual position while requesting active PWM1 to 50% for 15 seconds.
3. Is the EGR actual position reading between 42% and 58%?
   1. If yes, go to step 6 .
   2. If no, go to step 4 .
4. Remove the EGR valve.
5. Inspect the EGR valve butterfly for signs of excessive soot or white residue.
   1. If heavy white residue is found, the cause is typically coolant contamination (possible EGR cooler failure). Repair the source of coolant contamination and replace the EGR valve. Refer to "98.4.1.1 Verify Repairs" .

      Note: If the vehicle sits for long periods of time, small amounts of white residue will be present due to moisture in the system.

   2. If excessive soot residue is found, repair the cause of soot contamination (possible CAC system leaks) and replace the EGR valve.Refer to "98.4.1.1 Verify Repairs" .
   3. If no contamination is found, replace the EGR valve. Refer to "98.4.1.1 Verify Repairs" .
6. Disconnect the EGR valve connector.
7. Inspect the connector for bent, spread or corroded pins.
   1. If connector damage is found, repair as necessary. Refer to "98.4.1.1 Verify Repairs" .
   2. If no damage is found, contact the Detroit Diesel Customer Support Center at 313–592–5800 for further assistance.

Section 98.4.1.1
Verify Repairs

Verify repairs as follows:‪

1. Turn ignition OFF.
2. Reconnect any electrical connections that were disconnected to perform the diagnosis.
3. Clear codes with DDDL 7.0 or latest version.
4. Start and bring engine up to operating temperature (over 140°F/60°C).
5. Verify operation is satisfactory and no warning lamps illuminate. If warning lamps illuminate, troubleshoot the codes. If assistance is required, call the Detroit Diesel Customer Support Center at 313–592–5800.