DL24 - Check EGR Valve For Binding

The fault has been isolated to either the EGR valve or Pressure Feedback EGR (PFE) sensor. Due to the nature of this 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 PFE 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 or equivalent if needed)

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

- Is Diagnostic Trouble Code (DTC) 326 or 327 still present?

Yes -- Replace EGR valve. Remove breakout box. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)

If either DTC is still present, replace PFE sensor.

No -- The original DTC 326 or 327 was the result of the EGR valve not fully seating. Testing complete.