P0400 — Exhaust Gas Recirculation Flow Malfunction
| Meaning | The engine computer has detected a problem with the flow in the exhaust gas recirculation system, which routes a portion of your exhaust back into the engine to reduce emissions. This usually means the pathways are blocked with carbon buildup or the valve itself is stuck and not moving as commanded. |
| Family | Powertrain (P) |
Typical symptoms
Rough idling when the engine is warm
Engine hesitation or stumbling during acceleration
Common causes
Stuck or faulty EGR valve
Clogged vacuum lines or failing pressure sensor associated with the system
What to do
Frequently asked questions
What does code P0400 mean?
Exhaust Gas Recirculation Flow Malfunction. The engine computer has detected a problem with the flow in the exhaust gas recirculation system, which routes a portion of your exhaust back into the engine to reduce emissions. This usually means the pathways are blocked with carbon buildup or the valve itself is stuck and not moving as commanded.
Can I keep driving with code P0400 active?
Yes, no known limitation
Common causes — P0400
Heavy carbon buildup blocking the EGR passages or valve Stuck or faulty EGR valve Clogged vacuum lines or failing pressure sensor associated with the system
How do you fix code P0400?
Have a mechanic check the EGR valve and clean out any carbon deposits in the intake passages. It is best to address this soon to prevent rough running and potential damage to other emission components.
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Contact usRelated codes
- P0401 — EGR: insufficient recirculation flow
- P0402 — EGR: excessive recirculation flow
- P0403 — EGR control circuit
- P0404 — EGR: control circuit range/performance
- P0405 — Exhaust Gas Recirculation Sensor A Circuit Low
- P0406 — Exhaust Gas Recirculation Sensor A Circuit High
- P0407 — Exhaust Gas Recirculation Sensor B Circuit Low
- P0408 — Exhaust Gas Recirculation Sensor B Circuit High
- P0409 — Exhaust Gas Recirculation Sensor A Circuit
- P040B — EXHAUST GAS RECIRCULATION TEMPERATURE SENSOR 1 CIRCUIT PERFO...
- P040C — EXHAUST GAS RECIRCULATION TEMPERATURE SENSOR 1 CIRCUIT LOW
- P040D — EXHAUST GAS RECIRCULATION TEMPERATURE SENSOR 1 CIRCUIT HIGH