OBD
P04D9
Closed Loop EGR Control At Limit - Flow Too Low
What it means
P04D9 means Closed Loop EGR Control At Limit - Flow Too Low.
Check these first
- A clogged EGR passage limiting flow
- A stuck EGR valve
- A failed EGR flow sensor
- A vacuum leak into the intake
What to do next
- Command the EGR valve open and watch flow on a scan tool
- Clean the EGR passages and valve
- Check the EGR flow sensor signal
- Smoke test the intake for a vacuum leak
- Clear the code and retest
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Updated
Generic SAE J2012 definition. Last updated 2026-10-10.