This map allows to manage the exhaust gas temperature to protect the DPF and the turbocharger against possible overheating and consequent breakdown of these components.
It is a protection map that reduces the power, by putting the engine in protection mode once the ECU reads an excessive temperature from the sensor on the exhaust.
Generally, with the standard vehicle, this problem never occurs but, with tuned engine parameters – turbo pressure and fuel quantity – it will be necessary to raise the maximum permissible temperature threshold, to avoid recovery.
Note: the problem appears generally while driving long distances with medium or high revs and high engine load with long gears (5th or 6th gear), this because the more fuel is injected in the engine the more heat will be generated in the exhaust system.