Limp Mode is a protection strategy used by an ECU when it detects conditions that may require reduced
engine performance.
Possible triggers can include:
incorrect boost pressure,
fuel pressure problems,
sensor inconsistencies,
torque model conflicts,
critical system faults.
This is why Limp Mode is often not the actual problem.
It can simply be the ECU's response to another problem.
Sometimes, after a software modification, the vehicle may enter limp mode. In such cases, you can disable limp mode in a controlled manner.