In French, "APC" stands for Après Contact , which translates to . The A9B7 error occurs when the Engine Control Unit (ECU) detects that the relay responsible for powering the electronics when the ignition is on is either not working properly or is constantly receiving 12V power when it shouldn’t. Code défaut A9B7 - Le monde du diag auto

While this sounds intimidating, it is a known issue within the PSA Group (Peugeot/Citroën) community, frequently stemming from a faulty fuse box rather than a major engine failure. What is the A9B7 Code?

When you plug a diagnostic tool into a modern Peugeot—such as a 308, 5008, or Partner—and see the code , it indicates a specific electrical issue related to the ignition system. This code, often accompanied by warnings like "Engine repair needed" or "Emission control fault," is generally defined as a "Fault in the ignition positive relay (+APC) or in the output harness from the relay: Short circuit to positive" .