Door lock problem ..can open but can't lock

Will that door unlock from the master switch at the drivers door or the rear left doors own switch ?

does the dome light come on when the drivers door is opened, if not the pin switch is bad

driver side has most use and breaks down quickest.
Typically, the lock wears, and should be oiled using graphite powder, not oil, as with most outdoor locks.
However, in winter moisture turns to ice and freezes lock.
In this case, try to squirt lock de-icer (usually this is methyl alcohol or some other type).
Don't use an alcohol (such as from drugstore) that also contains water.
that would make matters worse.
If you spray enough lock deicer or even a high-quality penetrating oil, you may be able to work key and lock to a point where you can turn it.

Don't force key rapidly or too strongly, as it will bend, and may break off in lock.

You can spray some alcohol or penetrating fluid on the key to work it into the lock better.
Sometimes, you can get at a frozen lock mechanism by spraying down into **** between window and metal door from above lock.
Sometimes, you might find that the door itself is frozen,
or the lock latch is frozen, and not the key-tumbler.
In this case, you can try body-checking (not kicking) the door,
to loosen the frozen edges around door and window.
If you can get into car from other side, you can sometimes open it from inside to break ice-jam.

If this is an electrical problem (only remote doesn't work)
The likely cause is broken wire in wire-harness from car body to door.
There will usually be a group of wires either inside a cable or bundled in a rubber tubing, going from car to door at front between hinges.
Here is where the electrical connection will be broken,
because the wires break eventually as they get flexed over and over.

IN this case, the only permanent fix is to find the wire (it will be color-coded), and replace at least 6 inches of that wire (it will probably be broken inside insulating sheath.)
Alternately, there may be an open-circuit at connector to door-latch solonoid. Here you might get lucky if you get inside door-cover off and wiggle or re-insert the plug connector.
Also possible that solenoid is just burnt out or open-circuit.
In that case it must be replaced, for the remote signal to effectively open door lock.

Remote Transmitter Replacement (Wagon)
Use the following procedure when replacing one or both remote transmitters:

1. Open the driver's door.
2. Press and hold the driver's master door lock switch down in the UNLOCK position.
3. Quickly insert and remove the key from the ignition switch five times, then insert the key the sixth time, and leave it in the ignition switch. (This routine must be done within 1O seconds.) All the doors will lock and unlock to indicate that the control unit is in the program mode.
4. Press either button on the replacement transmitter. All the doors except the driver's door will lock and unlock to indicate that the control unit has accepted the transmitter into its memory. If either transmitter button is pressed again, all the doors will lock and unlock.
5. To program a second transmitter, press either button on that transmitter. The doors should lock and unlock as described in step 4.
6. Release the driver's master door lock switch.
7. To exit the program mode, close the driver's door or remove the key from the ignition switch.

The only time my doors don't lock with the remote is when a door is open. If your problem is mechanical it wouldn't unlock. Might be a sensor thinking a door is open. Does the other functions with the remote work like rolling the windows down or hitting the lock button flashes the light ? I can't lock my doors from the inside with the remote.

The computer detected a fault. You SHOULD NOT drive it around with that blinking, or you will regret it. Take it to the dealership immediately and have them pull the code.

I have the same problem in my accord 2004 but i can open it by hand. the suggested solution is to change door centre look or whatever they name it and this will cost you some money but solve the problem.

you could have a shortage in the main switch on the driver side door or the solenoids gone bad