Limp mode is a protective strategy built into the engine control unit. When the ECU detects a serious fault, it limits power and engine speed to prevent damage to the turbocharger, the diesel particulate filter or the fuel system. The car loses power, but can usually still be driven carefully to a safe place.

This page collects our limp mode guides: what it means and how serious it is, the common causes (clogged DPF, EGR faults, turbo and actuator problems, throttle body issues, transmission faults) and the related codes such as P0400, P0471, P2463 and P2563.

Limp mode is not the fault itself, but the signal that one exists. That is why each guide shows what to check first, which codes and live data to read with a scan tool, and when the problem is not where it seems. The articles are written for roadside and mobile diagnostics, based on real cases.