EGR valve

I cannot tell you how many more year's life you have left in your car. But as far as your code goes did you mean you have a P1404 not a P0104? As far as them replacing the EGR valve and clearing the code that should have been the end of the repair. The light should not have come back on and the same code should not have been set again. No learning in there being you on that one. I posted the code description for code P1404 so you have a better understanding on what is going on.

Are you sure it was not a P0404, as it appears a P0104 does not exist for your vehicle. P0404 is an EGR fault code. I would be skeptical in the fact that the diagnosis was correct. The check engine light should go away, as soon as the conditions that set it no longer exist. If it was a faulty EGR, and the valve was replaced, the conditions should no longer exist. This would especially be the case, if the codes were cleared post repair. It would require another diagnostic code scan to determine if the code is the same. If it is, some further diagnosis would be necessary to determine where the fault lies. There is a five volt circuit, a low reference(ground) circuit, and a signal circuit for the EGR valve position to function correctly. All these come from, and are monitored by the ECM. A problem in any of these circuits may also give you the same fault code. As far as how much longer you can expect this car to last, there are a lot of factors that may determine that answer. If your meticulous about your care and maintenance, that is going to prolong the life. When it becomes the time that repairs are getting to be more than the car is worth, that is when the decision needs to be made to keep, or get rid of the vehicle.

Here is the code description for code p1404 I forgot to post it on my first post sorry about that. What you need to do is take it back to the dealer that charged you to fix it. You need to make them fix it at no additional charge.
Circuit description:
The exhaust gas re-circulation (EGR) valve position sensor is monitored by the power-train control module (PCM). The five volt reference circuit, low reference circuit and the EGR valve position signal circuit are used by the PCM to determine the EGR valve position. When the ignition switch is turned "on", the PCM records the EGR learned minimum position. The PCM compares the EGR learned minimum position parameter to the EGR position sensor parameter. If the PCM detects that the EGR valve is still open when the PCM is commanding the EGR valve closed, DTC P1404 sets.

Conditions for running the DTC:

* The engine is running.
* The Ignition one signal voltage parameter is between 11-18 volts.
* The EGR valve is commanded to zero percent for twenty seconds after the EGR valve has been commanded to open more than forty percent for 0.5 seconds.

Conditions for setting the DTC:

* The EGR position sensor parameter is 0.2 volt more than the EGR learned Minimum position parameter when the desired EGR position parameter is commanded to zero percent for twenty seconds.
* The EGR position sensor parameter is more than forty percent and is steady for 0.5 seconds after a test failure and before the next test will be run.
* The above conditions are met four times.

Action taken when the DTC sets:

* The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the failure records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the freeze frame and updates the failure records.

Conditions for clearing the mil/DTC:

* The control module turns "off" the malfunction indicator lamp (MIL) after three consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, last test failed, clears when the diagnostic runs and passes.
* A history DTC clears after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Clear the MIL and the DTC with a scan tool.

Diagnostic aids:

* Inspect for excessive deposits on the EGR valve pintle or seat. Remove the EGR valve and check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.
* If the problem is intermittent, refer to intermittent conditions.

If you had the diagnosis and the repair done at the same facility, I would return to them and state that it was not fixed correctly. If they diagnosed it as a faulty EGR valve, Then it was an improper diagnosis, and you should not have to pay for further diagnosis.