Hi
On the 2.3 Litre models, the heater O007 is in a rubber hose (about 30 mm diameter) on the right hand side of the engine, above the gearbox (see picture).
According to my data, the 3.0 Litre models are not fitted with this heater, but it might be worth checking anyway.
A Fiat dealer will be able to read the full 7 digit error code (introduced 2013), for example P1581-XX, where XX are two supplementary digits. These "symptom identifier" digits will give a closer indication of the fault.
00 = Not specified
04 = Open
11 = Short to ground
12 = Short to B+
13 = Open
14 = Short to ground or open
15 = Short to B+
16 = Circuit voltage below threshold
17 = Circuit voltage above threshold
18 = Current below threshold
31 = No signal
44 = Data memory failure
47 = Controller failure
49 = Internal electronic failure
51 = Not programmed
62 = Signal comparison failure
64 = Plausibility failure
72 = Actuator stuck closed
74 = Actuator slipping
77 = Commanded position not achievable
7E = Actuator stuck on
1A = Circuit resistance below threshold
1C = Voltage out of range
1D = Current out of range
23 = Signal stuck low
24 = Signal stuck high
27 = Single rate of change above threshold
29 = Performance signal invalid
2A = Stuck in range
2B = Signal cross coupled
2F = Signal erratic
7F = Actuator stuck off
85 = Signal above allowable range
87 = Missing communication message
93 = Performance no operation
96 = Component internal failure
9C = Low insufficient flow
9E = Stuck on