Passenger side door lock will not unlock

sounds like you have 2 differant issues! but maybe one cause first the passenger door latch has failed or the wiring to it as gone open circuit poss inside the door wiring grommet because its got a double locking system so to unlock the passenger doors and boot you normally have to press the unlock button twice so perhaps the locking module is confused sort out the passenger latch first it then it should return to normal operation good luck

1. broken / loose wire
2. power door latch broke/defective. ( operating solenoid in latch is bad).

door lock actuator inside the door itself would be the best place to start!

change the batteries in the remotes

I vote for corroded or loose cable inside door.

Hold down the "open" button on your remote and simultaneosly pull the inside handle of that door open. I just had the issue with my driver's door and as my son tried to "help" (he's 9), one of the passenger doors also got stuck! After not finding a non-tech response, played around some until the the dran latch obliged on the front door. Repeated on passenger door and whew! :-)

needs door lock actuators... and all the door latches need cleaned and lubed... spray brake cleaner on latch let dry then spray some wd-40 or equialant on latch... it may need latches too but usually cleaning them will fix them

If remote locks and unlocks driver door but does not unlock passenger doors,then follow the advice above:
Get in the car using the key to unlock the doors. From the passenger side lock and unlock your doors using the button on the passenger door. Get out and the remote should now unlock all the doors with 2 presses.
Worked perfectly for me after several other suggestions (and dealer) failed.

I had problem with the door not opening from the inside because my kids put the child latch on.

Hello, we have a 2003 Kia Rio- problem as above- unlocking and then locking- only way in and out through passenger door.
This is what I have done and everything is back to normal- I hope it works for you.
1 Remove 25AMP fuse that controls door central locking from main box under the bonnet.
(AT this stage my passenger door opens- drivers side does not, the mechanism won't fully rotate)
2, Spray key with WD40 (or similar moisture repellent lubricant). Gently turn key to loosen mechanism- Partly remove key and spray lubricant into lock, have fun locking and unlocking!
3, Replace 25 amp fuse
4, Write yourself a cheque for garage labour and parts and wife brownie points!