DPF question and a few VagCom fault codes

On the motorway the other day, the DPF warning light came on and engine went into limp mode, before pulling up, turning off the engine etc resolved it. I was under the impression that only happens when the DPF fails to regenerate itself and the recommended solution is a 40mph sprint for a few miles. However, I only ever do motorway miles with no short trips where the engine doesn't warm up enough...so any ideas as to why this happened?

Also been presented with the following fault codes, (after clearing pre-existing ones, and there not being any when I checked it before buying) although they all seem minor based on a few searches on brisky. Am I right in thinking they're nothing to be too alarmed about?

• 05784: Please Check DTC Memory of Steering Wheel Electronics. (But cruise control is working fine).
• 02071 - no signal: Local Databus: No Signal/Communication. Possible Symptoms: Control Modules connected to Local Databus not functioning. (Where do I find the Control Modules to check connections?)
• 01520 - no signal: Rain and Light Recognition Sensor (G397): Implausible Signal. Possible Symptoms Rain/Light Recognition Sensor (G397) not functioning. (but the wipers on the intermittent mode seem to vary their speed automatically).
• 01135 - no signal: Interior Monitoring Sensors: Open Circuit Possible Causes Wiring/Connector from/to Interior Monitoring Sensors faulty, Interior Monitoring Sensors not installed. (Where are the interior monitoring sensors?).