[Engine] Thermostat, Coolant, Engine temterature

[Gorilko]

Hello everyone - first post 
Berlingo Multispace 1.6 vtr 16V, 2011, 72Kw, 7J5FK0, 120000miles 
This March regular service done + thermostat kit with electric switch changed (as per invoice).
Since than engine temperature hardly pass 70 degrees on dashboard gauge. Before it would get to 90 and stay there. During summer time I would need to drive it long time to get to normal 90 degrees.
In October went to mechanic to check it out. Oxi sensor (lambda sensor as per invoice) replaced due to fault.
Things went to normal until yesterday. I had 200 miles round trip on motorway yesterday; today engine temperature hardly passes 60-70 degrees on dashboard (as per OBD app. Coolant temp 61 degrees celsius).

Generally happy with car, purchased it mid 2019, it turns to be a bit juicy 34mpg local drive (maybe I need to adjust to petrol engine).

Any ideas what might cause affect engine operating temperature. Any chance new part installed to be faulty? Lastly, would thermostat replacement be ok for DIY-er and where do I find part number?

Thank you

[cancunia]

Welcome to the forum.

I think that maybe your new thermostat sensor is faulty. Does the heater get warm / hot air?

For parts, look on http://www.catcar.info/citroen/?lang=en

Input your VIN or follow the menu through to the corrrect model.

[Gorilko]

Thanks for reply. Definitively not hot air, I would say just mild.

[cancunia]

Maybe there is an airlock in the system? I am not sure how to bleed that air on the petrol engines.