The air intake hose or air bellows between the housing of the air filter and the manifold is particularly sensitive. Cracks and air leaks falsify the values measured with the temperature sensor, as warmer air is drawn in from the engine compartment.
They are also often hairline cracks that are difficult to see with the naked eye. If damage is suspected, the air intake hose must be carefully removed and illuminated with a hand lamp.
The air intake hose (VOLVO #682043) is available from spare parts dealers. However, repairs can also be made with special fabric tape (Power Band, duct tape).
The air intake hose is secured at each end with a hose clamp (VOLVO #951797, D = 67 mm, 12 x 50-70 mm). Do not overtighten to avoid damaging the material.