OBD-II code family
EGR Flow Control and Feedback Faults (10 codes)
10 related fault descriptions. Use each full code and the exact vehicle service information to identify its circuit, monitored condition, and required tests.
Codes in this family
This is the complete published member list for this guide. Each code retains its own page; shared diagnostic context does not mean that every member has the same test or repair.
- P0400Exhaust Gas Recirculation Flow Malfunction
- P0401EGR Insufficient Flow Detected
- P0402Exhaust Gas Recirculation Flow Excessive Detected
- P0403Exhaust Gas Recirculation Control Circuit Malfunction
- P0404Exhaust Gas Recirculation Control Circuit Range/Performance
- P0405Exhaust Gas Recirculation Sensor 'A' Circuit Low
- P0406Exhaust Gas Recirculation Sensor 'A' Circuit High
- P0407Exhaust Gas Recirculation Sensor 'B' Circuit Low
- P0408Exhaust Gas Recirculation Sensor 'B' Circuit High
- P0409Exhaust Gas Recirculation Sensor "A" Circuit
What these codes mean
P0400 concerns EGR flow; P0401 and P0402 distinguish insufficient and excessive detected flow. P0403 concerns control, P0404 range/performance, P0405/P0406 sensor A low/high, P0407/P0408 sensor B low/high and P0409 sensor A’s circuit. The categories answer different diagnostic questions. A valve position, electrical signal and amount of recirculated gas are related measurements, not substitutes for one another.
Read the complete manufacturer code and suffix. The covered Ford systems can express specific flow, stuck-control and position-feedback conditions as suffixes on P0400, P0403 and P0409. A short five-character display can therefore hide a useful distinction. The actual engine determines its valve design, pressure/airflow feedback and monitor conditions.
The sensor letter does not establish a temperature thermistor, cylinder bank or mounting position. FCA STAR S2025000005 Rev. A identifies P0407/P0408 as low-pressure EGR valve-position circuit faults in its applications. GPOP 9004343 separately warns against replacing the high-pressure EGR valve for those codes on listed MY2020–2021 JL/DT vehicles. Diagnose the identified system rather than choosing a part from the letter alone.
Validate feedback before drawing conclusions about flow. A valve that follows command can coexist with a restricted passage or cooler; an inaccurate pressure or airflow signal can distort the flow result. A high/low circuit code is not a direct high/low exhaust-flow measurement. Unplugged bias, a smooth PID or one normal resistance value does not universally identify a failed or healthy component.
Keep initial inspection cool and non-invasive. A technician should use the specified order for circuit, hose, control and flow checks, then clean or replace only the confirmed serviceable fault. Do not force an electric pintle, jumper unknown pins or push deposits into the engine. The national EGR-valve price is a conditional replacement-job example; the diagnostic-labor price on circuit pages is a separate service. Neither is a complete budget for every EGR code. Stalling, serious power loss, overheating, a flashing lamp or exhaust fumes require prompt assessment rather than a fixed waiting period.
Identify the circuit on your vehicle
Match the full DTC, reporting module, and any failure-type suffix to the service information for your exact year, make, model, engine, and equipment. An identifier alone does not establish installed hardware count, location, connector pinout, or a universal measurement.
Where the manufacturer publishes its own meaning for this code, that is the one to work from — it describes the actual component on your vehicle, which the generic definition cannot. Keep the generic description for what it is good for: it tells you which subject area the standard assigned the code to, which is useful context when the two appear to disagree. If they do disagree, follow the manufacturer.