P04D9
Closed Loop EGR Control At Limit Flow Too Low
Generic OBD-II
Real-world scan data
Seen in
98
scans in the past year
Found in
<0.1%
of scans
<0.1%
of scans that found faults
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check for any intake manifold or EGR valve blockages and clean if necessary.
- Inspect the EGR valve for any malfunction or carbon buildup and replace if needed.
- Verify the integrity of the EGR system's vacuum lines and hoses and replace any damaged components.
- Check and clean the EGR passages in the intake manifold.
- Perform an EGR system reset and relearn procedure.
Common causes
Most likely first
- Malfunctioning EGR valve
- Clogged or restricted EGR passages
- Faulty EGR solenoid or sensor
- Vacuum leak in the EGR system
- PCM (Powertrain Control Module) software issue
How to diagnose & fix
Work through it in order
- Check engine light illuminated
- Engine hesitation or stumbling during acceleration
- Decreased fuel efficiency
- Rough idle
- Engine stalling or difficulty starting.
Read & clear P04D9 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.