CEL Coming on and Turning Off

[TorqueEffect]

Could be a coolant sensor as well, that was an intermittent CEL for me.
The cheapo Masterpro sensor from O'reily's cured that for me, I don't think there is a preferred brand of those, at least I have never heard it discussed here.

Now I heard the comptuer does store codes until the car is turned off, maybe you can trip it, drive back home then try and pull the codes with the car still running. I am not sure if that works or not, whenever I pulled codes and left the wire ground it ran like complete crap when I started it. So IDK.

[Prafeston]

I could try to trip it and pull over immediately and try to pull the codes then. Hopefully turning the car off with the CEL on will save it once it's turned off.

[bravekozak]

Just do like I did and disconnect the CEL. You will never have to worry about the CEL ever coming on again, losing any sleep, or spoiling your long trip.

[XFSE71]

I just leave a jumper wire connected to the self test connector all the time and when the light comes on pull over engine running and ground the jumper. there are only 9 codes.

[Prafeston]

So if you aren't turning the engine off does the CEL keep cycling through the trouble code when you ground the test connector? Cause obviously you aren't inside the car looking at the CEL when you ground the wire so you can't see when it starts to run it's trouble code.

[TorqueEffect]

I just leave a jumper wire connected to the self test connector all the time and when the light comes on pull over engine running and ground the jumper. there are only 9 codes.

EFI had more than that. According to the Haynes manual anyway.

These are the codes for EFI engines. (I excluded ones that say 94' and later)

01 = Ignition Diagnostic Monitor
02 = Camshaft Position Sensor
03 = Cylinder identification Sensor
06 = Vehicle Speed Sensor (I am not sure about this one, it doesn't say 94' and later but I don't think Festies have these.)
08 = Airflow Sensor
09 = Coolant Temperature Sensor
10 = Intake Air Temperature Sensor
12 = Throttle Position Sensor
14 = Barometric pressure sensor (Integrated into the ECU, If this is bad, you have to replace the ECU)
15 = o2 Sensor (Just a sensor malfunction)
16 = EGR Valve position Sensor
17 = o2 Sensor (Tripped by overly lean or rich combustion, so anything from intake leaks, to bad injectors, to misfires, or to fuel pressure)
25 = Fuel Pressure regulator control solenoid
26 = Solenoid valve (purge control)
34 = IAC Valve

So if you aren't turning the engine off does the CEL keep cycling through the trouble code when you ground the test connector? Cause obviously you aren't inside the car looking at the CEL when you ground the wire so you can't see when it starts to run it's trouble code.

It will cycle through the codes if there is more than one, if there is just one, it just repeats over, and over.

[Prafeston]

Thanks for the info guys. Gonna try to make a jumper wire before I live on my next trip tonight.

[XFSE71]

EFI had more than that. According to the Haynes manual anyway.

I use Ford ...

[Movin]

The festiva ecm does not have all the codes listed programmed as the 1.3 is the simplest of all ford or mazda computer systems

[Prafeston]

Wednesday night I tried running the codes by pulling over and doing the self test while the car was still running like XFSE71 said he does and when I started to ground the wire it was sparking a bit and when it first touched metal the car started idling much smoother and slower. Then while I was screwing down the ground wire more securely...and it was still sparking...the car just shut off. I was in a hurry so I just unscrewed it and hopped back in the car. Was I doing something wrong?

[TorqueEffect]

Wednesday night I tried running the codes by pulling over and doing the self test while the car was still running like XFSE71 said he does and when I started to ground the wire it was sparking a bit and when it first touched metal the car started idling much smoother and slower. Then while I was screwing down the ground wire more securely...and it was still sparking...the car just shut off. I was in a hurry so I just unscrewed it and hopped back in the car. Was I doing something wrong?

I don't think you were doing anything wrong. Like I believe I said before, when I grounded the pin and tried to start the car, it started, but ran like complete garbage, it barely stayed running.
Maybe we both were doing something wrong?

[XFSE71]

are you grounding the STI (Self Test Input) ? single y/gn wire black connector in the harness with (STO) and (FP). should be no sparks. 5V. count flashes. no smoke.

[Prafeston]

It was a yelowish clear connector. Single connector...not sure what colors it was. Was the only one in the area where the picture was showing.

[drumnerd33]

On most self test systems you are not supposed to have the engine running, only have ignition in the on position with engine not running. This may have been your problem though im not 100% on that because my festiva is not efi im just going by most cars that use the cel blink codes. Also the ecm should store every code it flashes even if the cel goes back off it will store them, all you should need to do is the self check in your driveway and it will display all stored codes.

[drumnerd33]

Prafeston if you are still struggling with this i can call my uncle at his shop and have him look it up on mitchel, it will give you every little detail on how to check the codes on the ecm.