DL52 - Check EGR Valve For Binding

The fault has been isolated to either the EGR valve or Differential Pressure Feedback EGR (DPFE) sensor. Due to the nature of the particular fault, the EGR valve is suspect because of its vulnerability to contamination and carbon build-up from the exhaust flow. If the engine runs rough at idle, this is a good indication that the EGR valve is not fully seated rather than a faulty DPFE sensor.

- Remove the EGR valve.

- Inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, binding, and other damage. Service as necessary. (Use Rotunda EGR Valve Cleaner 021-80056 if needed.)

- Reinstall EGR valve and rerun Key On Engine Running (KOER) Self-Test. Key ON Engine Running (KOER) Self-Test

- Is Diagnostic Trouble Code (DTC) 336 or 337 still present?

Yes -- Replace EGR valve. Remove breakout box. Rerun KOER Self-Test. Key ON Engine Running (KOER) Self-Test

If DTC 336 or 337 is still present, replace DPFE sensor.

No -- The original DTC 336 or 337 was the result of the EGR valve not fully seating. Testing complete.