I have a 97 Subaru legacy and I can't figure out why the CEL always stays on. Auto zone doesn't pick up any codes they cleared it. And I reset the ECU but as soon as I turn the key on (not starting it) the CEL is on solid. This is driving me crazy I can't figure this out.

Also my at oil temp light is flashing but stays on if the key is in the on position, could the tcu and ECU messing with each other making them both stay on?

Two small green connectors under the dash? Are they plugged together? They should be UNplugged. Plugging them in puts the ECU in test mode and will keep the CEL on.

They are unplugged, idk what's going on with this car apparently I have a CEL with no codes and tranny codes.

Probably need to check the TCU for codes then. There's a process to do that by plugging some wires together and doing a secret dance, and the AT light will blink any stored codes.

 

I think there's a thread here somewhere how to do it. Google will know.

I've tried that but it just does the 16 flashes, but why would my CEL stay on with no codes, I know I have to have a couple since my speedometer doesn't work

Would anyone know what's going on with this vehicle?

you may need a more sophisticated scan - freessm, or a dealer....? It does seem like a TCU issue.

 

as for easy DIY - start by a careful inspection of wiring, maybe some rodents have chewed thru some harness somewhere or a wire has been pinched or pulled by maintenance, repair work or a wreck. There are even some odd problems that can be caused by blown brake lights and brake fuses.

 

but, you may need a dealer or well-equipped shop to help with this one.

I would think a thing like CEL on and no codes would be mentioned in the FSM.

 

It's possible that the ecu output to the CEL is failed in the on state.

 

I'm guessing - I never had that sort of problem, and no model between 93 and

01.

Maybe I missed the 'memo', but you stated:

 

".... soon as I turn the key on (not starting it) the CEL is on solid."

 

This is the way it works b4 it's started....along w/the Battery, Oil, AT Temp, etc. lights. If the CEL stays on AFTER starting that's an issue and there are still codes, and if you have no Speedo, yes you'll get a CEL and likely the TCU has related codes since it uses info from the ECU, too. 

 

A common failure is the cable that connects to the Transmission - near the dipstick for the differential oil on the passenger side. Remove the sensor and inspect the tab @ the end of it.....they break a lot.

 

 

The 16 flashes only is an 'alert' that there's something AT-related. A regular - Autozone type- OBD2 scanner won't get 'em.

Here's how to get/pull the AT codes - LINK.