Monitoring Function: Rationality check
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2010 BMW M6, 2010 BMW M5, 2009 BMW M6, 2009 BMW M5, and 2008 BMW M6. However, it is still accessible from the selected car via links, so may be relevant.
The rationality of the ambient temperature is check with an IAT-based model. As soon as the difference between model and ambient temperature exceeds a threshold, the error counter starts to increase. As soon as the counter exceeds a threshold a fault is set.
Given steady IAT conditions or whilst warm-up cycle after a cold start, the ambient temperature is permanently compared to the model.
In very unsteady IAT conditions (e.g. after an up-heating period with idling or slow moving vehicle or after a warmstart) the diagnostics is suspended and is re-enabled after increasingly stabilizing IAT conditions.