Many thanks for your comments on my remote central locking problem.
I have not used the system as described in the reply to my problem as it seemed to refer to the infra red type of central locking system as fitted to earlier models and not the radio type that I have in my espace.
I can understand your doubts Ross but the system is virtually the same as it happens. The main difference is that you only need to press your plip once where an infra-red plip has to be pressed several times, for each good plip, whilst aiming the infra-red correctly.
The pick up for the remote is combined in the electronic dash panel on your car. The keys contain two systems, one for unlocking/locking the doors by remote (ultra sonic radio frequency) and a chip that the immobiliser system uses to protect the starting. When you press the plip it emits a signal which is picked up by the dash and if correct the central locking is operated. However, whether or not this works, the starting is a separate system entirely, as you know since your car will start. The chip in the key is 'read' by a reader ring around the ignition switch, so when you put the key in and turn on the code is read, passed to the immobiliser and provided it is correct, the system is unlocked and the engine is authorised to start.
Now the radio key signal for opening the doors, is on a rolling code system. So every time you press it the code changes. This is to stop anyone with a radio reader nearby from simply reading the code, and then once you have gone, using that code to open the vehicle. (this was possible on very early non-Renault systems with a fixed code). One fact of this rolling code system which is not properly explained to owners, is that you must use both keys frequently. It doesn't matter if you don't use one of them for say a week or two but eventually if it is not used for a long time, the one that is not being used will get so far out of sync. with the rolling (changing) code, that it can no longer work. As long as they are both used they both stay in sync. If or when one key does get out of sync. it is fairly simple normally to re-sync. it and then it will work again.
So in all likelihood you just need to synchronise the key that is transmitting and then use that one to open the doors and start the vehicle, and keep the second one as a backup that will at least start the car even though it cannot transmit and therefore work the doors.
I am right in assuming that the good key/plip i.e. the one that will transmit a signal, does start and run the car? Because if it doesn't you probably do have a serious problem. So can you first confirm please that both keys can be used to start the car now.
When I bought the car, about 18 months ago the private seller said that the problem with the central locking was a dead battery in the key.
That might have explained the reason for one key not plip locking but what about the second? It would be unlikely that both keys go flat at the same time!
I replaced the battery and it of course made no difference, so I took the car to my nearest Renault main agent and they told me that "their computer wouldn't talk to my car computer" so they advised that I have all the elements replaced, computer - dashboard and keys and have the system reprogrammed, all for an estimated minimum cost of £1000.
Replacing a complete system is only necessary if you have lost both keys. That is not the case here. So whilst there may be a problem preventing their computer interfacing with the car computer, I don't rule out that they have simply not done their job properly at this stage.
The first job should have been to synchronise the keys or in your case the one key that is working. For that they don't need the computers to interface.
So as long as the key that transmits does actually start the car already, proving it is the right key for your car, please follow these steps to attempt to synchronise it:
Unlock the doors manually as you have been doing and sit in the drivers seat. Put the key in the ignition and turn on. Do not start the engine just turn the ignition on, and note the warning light. It should come on for a second then go out. Now switch off and remove the key from the ignition switch. Immediately press the central locking button on the overhead panel and hold it pressed (it doesn't matter which side) until you hear the locks go clunk, clunk after about 5 secs. Then press the plip on the key, and the locks should respond. At the same time please watch the warning light on the dash. When you activate the system by pressing the central locking button and holding it for approx. 5 secs. the warning light should have come on. When you press the plip on the key and the locks respond, the light may go out or stay on. If it goes out, the key should be synchronised and it wil now work. If however, the warning light stays on for upto 20 secs. it is waiting for the second key plip to be pressed. In other words it is configured for two keys and it needs both to reset. You can try the one that you got off ebay, it might work, but don't expect it to. If it works with just the one good key, great, and if it works with both even better, but if it works with the one good key and then is waiting for the second, which you haven't got (and the ebay one is no good) then after timing out and the warning light goes out, you will probably find the good key will still not work at this stage.
What has to be done next is to reset the system for one key only, then resync. the one good key plip. This is possibly where you will need a diagnostic computer to interface with the on-board computer to reset it for one key only. At this stage, it may still be possible - don't take it for granted that just because the Renault dealer said they couldn't connect, all is lost, as they may not have done things correctly, or used some faulty equipment or software. There can be many reasons, but let's take it a stage at a time.
Go through the re-sync. procedure as I have described it. Please note exactly what happens and let me know how you get on. Also please let me have the car VIN and fabrication numbers as I may need that to get the four digit manual unlock code.