P0016 (Crankshaft Position - Camshaft Position Correlation) tends to suggests it’s either a chain that is starting to stretch or a bad cam/crank sensor (NOT solenoid). The cam and crank should be precisely timed together. If the ECU detects that the Crank and Cam signals are out of time by a specific number of degrees, then P0016 code will be set.
Have a look at this link:
P0016 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A) - DTC Code
Causes may include:
Timing chain stretched, or timing belt skipped a tooth due to wear
Misalignment of timing belt/chain
Tone ring on crankshaft slipped/broken
Tone ring on camshaft slipped/broken
Bad crank sensor
Bad cam sensor
Damaged wiring to crank/cam sensor
Timing chain tensioner damaged
The sensors usually have a narrow tolerance in order to pick up an impending problem with the parameter it is measuring. This does not necessarily mean a failure is imminent. For imminent failures, generally the ECU will put the engine into some form of limp mode or won’t allow it to run. For e.g. even with about 4 error codes I still ran about 700 miles before I bottomed out the chain as the most likely culprit as I had erratic idling and a noisy chain, although I never had the P0016 code and took the plunge to replace the chain and tensioner. I did manage to clear all the codes except P0010 and that was specific to intake solenoid which suggests there were two failures, one a stretched chain (since this cleared the other 3 codes) and two the cam solenoid (which cleared the P0010 code).
If it’s the solenoids I would expect one of these error codes: P0010, P0011, P0012 - for the Intake and P0013, P0014, P0015 for the Exhaust solenoid.
So with P0016 being the only error, it’s either a chain that is "starting to stretch" or one of the sensors (cam sensor or crankshaft sensor) is faulty. If you have access to an oscilloscope you could check the signal patterns of these sensors as described in the above link but I doubt even an Alfa dealer would do something like that and would only replace the sensors or do the chain. If possible checking the resistance of these sensors may tell if one of them is open circuit (high resistance) if you know what the factory value for the resistance is. I have e-learn CD and this doesn't have this info (useless for wiring and electrical data). I think these sensors have 3 pins each on the connector. Maybe someone else knows the resistance values or how to check them?
Alternatively, you could see if changing the cam sensor (possible) helps, if not the crank sensor (unlikely) and then eventually if these don't cure it then I am afraid its the chain (more likely). Stretched chains on the 159/Brera JTS engines is a well known issue. The chain doesn't fail, it just stretches enough for the cam phase sensor to notice a problem and bring the light on.
The cam phase sensor and crank sensors are about £25 for aftermarket and £45 for OEM depending on where you get them from I guess. FAI and other equivalent chain kits are generally what Alfa specialists use since they are decent quality and cheaper than the OEM version.
For the future I am definitely going to change the oil and filter every 8,000 to 10,000 miles rather than the 18,000miles recommended by Alfa!! I used to change the oil every 12k miles but the last time I left it till about 16k miles and then I had the timing chain issue. Not 100% sure if it’s directly related but various forums on this topic suggest a more frequent oil change will not cause any harm and will help protect the chain. Something to do with the oil nozzle port diameter for the chain lubrication side being only 1mm or so and needs to be larger which has been revised on some GM engines but not Alfa; in combination with poor quality of OEM chain material and the oil degrading over long change intervals resulting in blockage/poor oil flow through the nozzle and a stretched chain due to lubrication issues.
Disclaimer: this is my conclusion based on a lot of research on this very topic when my timing chain needed replacement.
Hope this helps.