So, I was driving home from my girl's place and I noticed that my CEL was flashing, got into the right lane and slowed down, checked all guages, everything checked out fine. Started to accelerate and I noticed that it stopped blinking and stayed on. I decided to test something, I let off the gas and the light went away while in decel, back on steady throttle it will start flashing again. Under load it stays on. Now when I start the car in the morning it's not on, but will come on, but flash rather than staying on steady, as the car warms up. I'm thinking it's my O2 sensor, but I'm not positive and I was wondering if anyone else has had a similar problem.

S14 sr, full turbo back exhaustApexi intakeHKS wastegate at 10psiNo tune

If you need anymore information, I might be able to supply you with it depending on what it is.

Thanks in advance guys, Glenn.

Pull the code off the ECU.

That would be the easiest way. You can rent one from Kragens or something can't remember which one. Or go to a smog place and see if they can read it for you, maybe a small fee.

I think advance or autozone should have ODBII readers. Of course, that's dependent on if he managed to get the wires for the consult hooked up.

the pin on the japanese computer that would be the MIL is actually the O2 Sensor monitor. when you see the light flashing it goes like this:

off = richon = lean

when you accelerate and go into closed loop... the light will simply stay in whatever position it was in when you brook the loop. my s15 puter does the same thing. there's no rhyme or reason to when it does it... sometimes it does, sometimes it doesn't.

there's nothing wrong with your car or computer.

I have the same problem, I took the battery cables off to erase the code and see if it return but it nerver leave , doesnt matter how long it is disconected. did you have the same problem?

So this thread turned up in an online search. My S15 ECU is just started doing the exact same thing. It started doing it when the state emissions guys tried plugging into the car's OBDII port. I'm fully aware that the OBDII port is essentially dead with my SR swap, but I needed an emissions "failure" to start the waiver process.

I have a Consult cable and the Nissan DataScan app on my cell phone. The ECU has code 55 "all clear." After monitoring the values for a few minutes, I can verify that the blinking CES light is related to the O2 sensor. The light comes on when the O2 sensor value drops and turns off when value goes back up.

Could an OBDII scanner have shorted something out in the ECU? I have a wiring specialties harness, and I'm assuming the OBDII wire just isn't connected at the F3 connector. Kinda stumped.

Car is a 97 S14, with S14a SR swap running on S15 ECU.

Solved! The ECU was in a diagnostic mode.

The "check" pin on the ECU was wired to the OBD2 port. I suspect wiring specialties did that on purpose so people who don't have a consult cable can put the ECU in diag mode, since the U.S. S14 KA doesn't have a "check" pin on the consult port.

Jumped the OBD 12v with the check pin for 2 seconds, no more wonky CEL.