P0408
Severity: LowExhaust Gas Recirculation Sensor B Circuit High
Last updated: July 2026
System
Powertrain
Subsystem
Auxiliary Emission Controls
Code Type
Generic (SAE)
Exhaust Gas Recirculation Sensor B Circuit High
Last updated: July 2026
P0408 is a generic (SAE) powertrain diagnostic trouble code. It is defined as "Exhaust Gas Recirculation Sensor B Circuit High". It falls under the auxiliary emission controls area of the vehicle’s powertrain system, and has the same core meaning across most makes and models.
The onboard diagnostic system sets P0408 when it detects a condition matching "exhaust gas recirculation sensor b circuit high" in the auxiliary emission controls circuit or system. When the fault is confirmed, the module stores the code and, in most cases, turns on a warning light.
This code is generally minor and often relates to a signal, range or performance condition. It should still be inspected, especially if it returns after clearing.
P0408 means "Exhaust Gas Recirculation Sensor B Circuit High". It is a generic powertrain trouble code in the auxiliary emission controls area.
This code is usually minor, and short-distance driving is often possible, but you should still have it checked — especially if the warning light stays on or the code returns.
There is no single fix. Start by confirming the code with a scan tool, then work through the likely causes and checks above — inspecting wiring, connectors and the relevant components before replacing any parts. On most vehicles, confirm the diagnosis before repairs.
You can clear the code with an OBD-II scan tool, but if the underlying fault is still present it will usually return. Clearing without repair is only useful to confirm whether the fault is active.
This information is provided for general reference only. It is not repair advice and may not apply to every make or model. Manufacturer-specific codes can differ. Always confirm a diagnosis with a scan tool and, where needed, a qualified technician before replacing parts.