Peugeot 206 rough start

[Rolland]

Hello there,
I have a Peugeot 206 and lately it starts up rough if it hasn't been driven that day, idling at 300-400 rpm then jumping to a normal 900 rpm after 3-4 seconds

It has to be noted that when the car starts up this way, the airbag light goes on, and when I restart the engine after this rough start it starts up normally, idling at 900 rpm, and no airbag light

I have the check engine light on so I bought an OBD tester and got an error code (P0170).

Any help is appreciated
Thanks in advance,
Rolland

[ozvtr]

That means the engine ECU has to adjust the fuel trim beyond a certain point. Either too much fuel or not enough fuel.
Suspects are; Upstream O2 sensor, Vacuum leak or injector problem.
I would be more suspicious of an injector, as it comes good after a few seconds.