Random CEL?

[94tanner]

Cruising down the highway today doing 70 in OD and CEL pops on, all guages read good, running perfectly, nothing out of the ordinary. It then proceeds to turn on and off in about 2-5 minute intervals. Sometimes it's on, sometimes off. I checked all fluids, looked at the exhaust system, checked for loose hoses/wires/connections, just can't find anything wrong.

So what is the likely culprit here? I'm thinking a sensor sending bad information, maybe the O2? Maybe my ECU is on it's way out?

'94 Ranger XLT / Ext. Cab / 4.0L Ohv / Automatic

 

[94tanner]

I also plugged in my OBD I scanner and am getting "000" in both active and stored codes... Nada. Maybe I'll go get it scanned professionally tomorrow and see if my scanner just isn't reading.

Sent from my SM-G925V using Tapatalk

 

[RonD]

000 is not an OBD code
111 is system test OK

So odd one, because OBD1 was setup to be checked with a meter or flashing light, "0" could not be used with OBD1, no OBD1 codes have "0" in them

You can unhook the battery for 3 minutes or longer to clear KAM(keep alive memory), system will do a fresh reboot when restarted.
Idle may wander a bit as computer relearns settings.
After reboot test OBD1 again and see if you get the 111

You can also test computer by unhooking a sensor like the IAT(intake air temp) sensor, upper intake drivers side, then drive it until CEL comes on, won't hurt anything.
Then test if you get an IAT code, 112, 113, 114

 

[Haywire6000]

My 93 2.3 would do that. It was a bad O2 sensor, granted you want to find out the issue before your shot gun parts at it but mine was doing the exact same thing. After he 02 got good and hot it would throw a lean code. Mine you could normally back off the throttle and withing 20 seconds the light would go out, get back into it and a minute or so later on again she would go.

 

[94tanner]

02 sensor or something exhaust related would make sense, I have a tiny leak somewhere on that system.

Hm, maybe it isn't reading at all then. It ran flawlessly all day today without a CEL so I'm guessing whatever it was rattled back into place I have some suspension work done so might be rerouted wires doing something funky. Who knows. If it comes back I'll try all of these solutions.

Thanks!