SB-14-012

A subject vehicle may exhibit an illuminated check engine lamp with DTC (Diagnostic Trouble Code) P0421 (Catalyst efficiency below threshold). The engine ECU may falsely detect an issue with the ATC (After Turbo Catalyst) with the current ECU software. If DTC P0421 is stored in the engine ECU, reprogram the ECU to the latest software level prior to suspecting a fault with the ATC.