Mk5 ambient air temp sensor

[HairyFool]

Doing other work trying up I found a device hanging loose under the steering reservoir. The part number identifies it as a temp sensor, it would do its job but should it be in something? Logically the airbox but there is no hole for it.

According to Haynes the colour codes for the wires are wrong. Is the wiring diagram in the Haynes known to be wrong, if so where can I find good ones?