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Diagnostic knowledge / P04D9 — Closed loop EGR control, limit reached - low flow detected
P04D9

Closed loop EGR control, limit reached - low flow detected

P04D9 is described as “Closed loop EGR control, limit reached - low flow detected” in the Generic OBD2 reference.

Some scan tools (for example GM and Ford dealer tools) display this code with a failure-type suffix, such as P04D9-00 or P04D9:00; the base code P04D9 is the same.

Generic OBD2

Generic OBD2: P04D9

en

Closed loop EGR control, limit reached - low flow detected

Reference namespace
obd2
Source revision
legacy-2.2.20

Generic OBD2 definition; confirm the protocol and vehicle-specific service information.

What should I check before using this definition?

Keep the full code, module, status and freeze-frame data. Confirm the vehicle’s make, model, year and current manufacturer service information before choosing a repair. This entry does not identify a failed part by itself.

Organize a scan report or recording
Source and applicability

OBD Lens production library legacy-owner-2026-11-02-v84-evidence. This is a scoped technical reference, not a scan of your car. A catalog relationship does not certify that every ECU, year or engine returns the same signal or code definition.

Read the reference method

What does P04D9 mean?

Closed loop EGR control, limit reached - low flow detected. 1 reference families define this identifier: Generic OBD2.

Is P04D9 a generic or manufacturer-specific code?

This code has a generic OBD-II prefix. Confirm the reference scope shown above.

Can P04D9 tell me which part has failed?

This entry does not identify a failed part by itself. Confirm the vehicle’s make, model, year and current manufacturer service information before choosing a repair.

OBD Lens reference library · catalog legacy-owner-2026-11-02-v84-evidence. Sources and scope