DL90 - All Continuous Memory EGR DTC: Intermittent Verification

NOTE: This test step verifies if the Diagnostic Trouble Code (DTC) is due to an intermittent or a hard fault.

- Perform Key On Engine Off (KOEO) and Key On Engine Running (KOER) Self-Test if you have not already done so and make note of all codes received in KOEO, continuous Memory and KOER modes. Quick Test Appendix (Detailed Testing Instructions)

If unable to run KOER due to a "No Start" or "Stall," do not continue with this step, but go directly to DL101. DL101 - Check Vacuum at EGR Valve

- If an EGR fault exists at the time of this test (hard fault), then an EGR DTC should also be received in KOEO or KOER or both depending on the DTC. If the EGR DTC is NOT received in KOEO or KOER but only retrieved from Continuous Memory, this could be due to an intermittent EGR system fault which occurred sometime in the past.

- Are there any DTCs output in KOEO or KOER Self-Test (ignore Continuous Memory DTC's at end of KOEO)?

Yes -- A hard fault is indicated. Refer to the Diagnostic Trouble Code charts. Manufacturer Code Charts

No -- An intermittent fault is indicated. Go to DL91. DL91 - All Continuous Memory EGR DTCs: Visual Inspection