Speebs

iTrader: (2)

I attempted to use the search function, but could not get any reliable results.

My CEL is stuck on. There are no codes, so my tool won't clear it. I don't want to reset the ECU, just turn off the light because I had to drive over 500 miles before it re-calibrated itself last time, and I need to pass emissions soon.

What do I do?

IlyaK

iTrader: (47)

How do you know there are no codes?

What did you use to figure that out? What kind of tool? Could be your tool is faulty. Try the screw driver method.

Speebs

iTrader: (2)

I used an OBDII tool I've had for a while. I doubt it's broken as I used it not long ago and it was pulling codes. I don't know the brand but it's orange and I got it at Pep Boys.

Isn't the screwdriver method going to reset the ECU?

pmohr

iTrader: (26)

If you clear the codes or turn off the CEL, either way it will clear the emissions readiness monitors.

And no, just checking codes manually won't reset the readiness monitors.

Speebs

iTrader: (2)

That's retarded. So there are no codes, but the light is still on, and the only way to turn it off is to reset the damn thing? wtf.

I do now notice that the catalyst system is not ready. Could that be triggering the CEL?

pmohr

iTrader: (26)

Again, have you not checked the codes manually? It's possibly the OBD-II reader isn't working properly.

And no, a not ready monitor will not light the CEL.

Speebs

iTrader: (2)

I have not. I didn't have a small enough screwdriver with me last time and it's raining right now. I just want to understand... you're saying that either my OBDII reader is broken, or my ECU is?

pmohr

iTrader: (26)

Not necessarily either. Sometimes the CEL will be lit for 0505/P0000 (which some OBD-II scanners refuse to interpret), meaning nothing's wrong. This can happen due to voltage fluctuations, charging system issue, etc.

Won't really know anything until you're able to check the codes.

Speebs

iTrader: (2)

Got it. But in that case, it seems stupid that you can't clear the light without resetting the ECU, since the light is indicating that there are no codes.

IlyaK

iTrader: (47)

You don't know if the light is indicating such. That is what me and PMohr want you to do.

Do the screw driver thing, let it flash to you. If it flashes 5 times, pauses, and 5 times again...that means you have NO CODES. However, as he mentioned, it could still mean you have a problem.

If the CEL flashes 3, pause, 5 or something, then you have the code you need. Keep watching it to make sure it's not 3 and 5 (or whatever) every time. It'll give you ALL the codes it has.

Search for the correct procedure.

njmaxseltd

iTrader: (19)

Some people just don't get it...

pmohr

iTrader: (26)

I think njmaxseltd finally snapped

Speebs

iTrader: (2)

Guys, if you look at my history, I have been here for a while even if I haven't posted much. I know how to check the codes using the screw method (even though when I exit the diagnostic mode it resets the ECU EVERY TIME, despite following the instructions to the letter).

From what you are telling me, my understanding is that the CEL CAN be on if there are no codes, but if that is the case there is no way to clear it without resetting the ECU. I'm saying that IF THAT IS THE CASE, it's stupid. If I'm wrong, then explain better.

I realize that for the last couple of years you've had to deal with an influx of complete idiots here, but instead of treating people like idiots right off the bat, try a little less elitism.

ATTappman

If the CEL is on and a working scan tool tells you their are no mature codes, then something is wrong. There's a fault somewhere. In that case, clearing the codes might make the CEL turn off, or it might not. You would have to diagnose why the CEL comes on for no good reason.

SrgScott

iTrader: (2)

Well really, when you reset the CODES you are not resetting the ECU.
And.....the three OBD-II scanners all have an option to "turn CEL off" wether there are codes or not.

And whats so bad about resetting the ECU anyway? Its not like it takes that long.

Speebs

iTrader: (2)

Please identify where the option is to "Turn CEL Off" because it's not in any menus that I see.

If you read my post, the last time the ECU was reset, it took over 500 miles of driving for it to be ready for testing. It does "take that long."

pmohr

iTrader: (26)

Are you following the correct driving cycle, or are you just driving around?

If you actually follow the correct driving cycle, it doesn't 'take that long'. If you don't bother doing it correctly, and just drive around normally, it could take a long time.

Crusher103

iTrader: (10)

not all code readers will read all code, i suggest going to autozone or advanced auto and have them plug in theirs and see what happens it could be just ur code reader thats not picking anything up.

Speebs

iTrader: (2)

If you mean the one that is extremely dangerous to do on public roads, no I have (and will) not. Is there another one?

MaxGordon7

iTrader: (36)

Just reset the ECU! I have never heard of just turning the light off without reseting the codes in the ecu but I have only used basic readers.

pmohr

iTrader: (26)

Can you post the one that you feel is 'extremely dangerous'?

Without any specifics, I have no way of saying whether or not you're referring to the correct drive cycle.

MaxGordon7

iTrader: (36)

In the fsm there is a driving style that will cause the ecu to test sensors correct?

Speebs

iTrader: (2)

I don't remember the cycle exactly, but I believe it entailed driving for a few minutes at highway speeds then quickly dropping down to 20 or 30mph. I don't know of anywhere safe to do this other than a track.

pmohr

iTrader: (26)

You don't have to do the entire drive cycle at once (otherwise you wouldnt've done it even after 500 miles), it can be done in stages.

FWIW only certain monitors are set ready by certain parts of the drive cycle, so you could just do them one at a time.

DTrem08

iTrader: (3)

highway to offramp.