The check engine light on my '03 Protege will come on intermitently and then go off. But now it's flashing. Any idea? TIA.

 

You need to go to an auto parts store and have them scan the codes. Write the codes down and list them for us.

When the CEL flashes conditions are such that the catalytic converter may get damaged if you continue to drive the vehicle.

You can borrow the scan tool and read the codes yourself.

 

the first question that comes to mind is: does the car feels different when the lamp flashes? does it blinks in a steady pattern or is it at random? how many miles does the engine has?, etc. the first thing to do is to follow tanprotege advise. get all the codes, even the pending ones if present. get the maf airflow numbers, engine load %, short and long term fuel trims, both o2 sensors activity (how fast the upstream sensor changes readings compared to the o2 sensor downstream and max/min values of each one), coolant temperature and intake air temperature, and the baro readings. (all that should be available if you pay to get the codes). it could be something as easy as replacing a spark plug cable or spark plug , up to something more serious.

 

A blinking cel usually means a misfire.
Change all plugs and ignition coils if you haven't yet.
Spark plug wires should be changed as well if there are some.
That's what i would do. while you're there, clean the throttle body, clean the maf sensor, change the pcv valve and clean the egr. I'm sure they are due as well, mind as well do them.
Re-set the ecu.

 

Moth, My 2003 P5 has 148K miles on it and I need to take it back for a fourth time today. First time if flashed I lost power and then it came back after ten minutes of driving. But i had the EGR valve replaced. Next day it happened again and the dealership said it was the ignition coil and spark plug wires. I got it back and the next day the light came on but did not blink. But it stayed on for 2 weeks then i felt a misfire and the dealership replaced a fuel injector. I just got it back and now I have a the solid check engine light for a fourth time. Everything runs fine otherwise and I would really love to keep this car for another 50K miles before i have to trade it in for a family sized vehicle.

 

it would be easier for us to help you if you could tell us what code you have.