OBD-II DTC · SAE J2012
P0406
Exhaust Gas Recirculation Sensor A Circuit High
What P0406 means
P0406 is a standard SAE J2012 powertrain diagnostic trouble code with the defined meaning: Exhaust Gas Recirculation Sensor A Circuit High. This is the OEM-agnostic definition; specific manufacturer interpretation may add detail (subsystem, bank, sensor location) but the core meaning is consistent across all OBD-II compliant vehicles since 1996.
Can this code be suppressed via ECU tuning?
Very common service. EGR mechanical failure (sticking, carbon buildup) often pairs with ECU-side EGR off. Off-road or motorsport only.