[Atyn]

If it's the n13 b16 engine the sensors are on top - see photo.

However more likely to be the valvetronic mechanism or actuators and both of these are not easy to get at.

 

[Atyn]

BMW Fault Code Lookup - BMWFaultCodes

Look them up. But 1339 relates to exhaust camshaft so looks like your issues are all related to the vanos.
Could be a faulty sensor.

Cam sensors are about £14ea from Autodoc so not too costly if they didn't cure the problem.

https://www.autodoc.co.uk/abakus/13300192

Enter your reg no. to find the correct part.

P13C0 is intake vanos and the above site suggests intake solenoid but click on 'view' for more into. Note the comment about oil pressure - when was the oil and filter changed?
Might be worth using some engine flush if they need doing.

The intake solenoid is on the drivers side at the front under the ecu but fortunately more accessible than the exhaust one on the opposite side.

The solenoids are £36.

https://www.autodoc.co.uk/car-parts/control-valve-camshaft-adjustment-15036/bmw/1er-reihe/1-f20/10311-116-i

 

[Atyn]

Don’t even bother trying to re-time it if it’s off it’s off for a reason. Most likely stretched or guides breaking up.
Do a complete chain kit along with sump removal and clean sump/oil pick up to make sure no debris.

The cam chain kits with or without new sprockets and the tools needed are reasonably priced om ebay and videos are on Youtube.

The chain, complete with guides just drops in from above so no major dismantling.

I plan on doing mine in the summer.

 

[Atyn]

@Johnnyroper @Atyn could either of you refer a link to a set of tools for the locking of the camshafts please?

Help yourself it's not hard to look on ebay or Amazon:

https://www.amazon.co.uk/Dayuan-Engine-Camshaft-Timing-Cooper/dp/B07V2MDC6V

Same for the chain kits.

 

[Atyn]

I saw a comparison of a N13 chain - original and new one on YT. There was a big difference - looked about 10mm.

Definitely a mistake not to change the chain and guides. Don't be surprised if the codes return.