Without the proper diagnostic code I cannot entail what portion of the EGR system has failed, but at this milage i'd say the code was most likely related to the flow of the EGR sytem. This is commonly caused by the EGR vacumme modulator, which controls the valve. At this milage I would say the valve itself was most likely not the cause of the failure, without proper testing most technicians "guess" the valve is the culprit. In any case if the valve is replaced the modulator should be done as well. The modulator itself, is much less costly than the valve as well. Below is a diagram of the EGR system, you should ask them for the original part when you take it back in, and have them describe to you how it has failed, whether the valve was plugged with carbon and frozen, or the vacumme diaphram not holding, possibly they could test it in front of you. You can also have them test the modulator, any experienced Toyota tech will know hoe to quickly condemn the modulator. The valve may have lasted you another 50-80,000 miles if it wasn't bad. The check engine lamp comes and goes,because the computer is constantly self testing the EGR sytem, if it no longer sees the fault within 40 ignition cycles it resets the lamp, and than waits for the fault to reoccur twice before it will set again. Also, after a lamp reset from the repair shop it will take two consecutive faults again to turn the lamp on.

-Rip