Help-check engine light

My check engine light just came on. How do i get it off ? 1999 80K miles

1. go to the local AutoZone, and ask them to connect an OBD-II scanner to your data bus connector under the dash. This will read the fault codes from your engine control processor that have triggered the light to come on.
2. repair the circuits/elements that are indicated by the codes.

Get the code(s) read. AutoZone will do it for free. Come pack here and post the P codes you find. Fix the problem, and the light will go away after 50-100 drive cycles.

AZ Jeff said:

1. go to the local AutoZone, and ask them to connect an OBD-II scanner to your data bus connector under the dash. This will read the fault codes from your engine control processor that have triggered the light to come on.
2. repair the circuits/elements that are indicated by the codes.

Click to expand...

Wow, lotsa big, technical sounding words there

This means i have to start and stop my engine 50 to 100 times before the light goes out ?

anony91xj said:

Wow, lotsa big, technical sounding words there

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Sorry, the engineer in me comes out when the problem is technically complex in nature, as is the case here. It's also factual, though, so I didn't make up a BS answer.

sjan said:

This means i have to start and stop my engine 50 to 100 times before the light goes out ?

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No, you can disconnect your battery for a while and then reconnect it, thereby cancelling the fault codes stored in memory.

Once you fix the problem, OBD-II calls for either 50 engine run cycles to clear the code, or for the code to be cleared externally once repaired.

All this is moot if you don't know what the problem is - because if you don't fix it before you clear the codes, you'll get the CEL/MIL again, with the same code! Get the code(s) and fix the indicated issues first - it may even be something simple - like fuel filler cap not venting properly, or somesuch. You won't know until you have the codes read now, will you?

If you've got an Autozone handy, they'll read the codes for you. If you're going to keep this vehicle for a while, or buy mainly OBD-II vehicles (1996 and later,) you'll want to buy a hobbyist reader - which should run something less than $200. That way, you won't have to run off to get the codes read every time the CEL/MIL comes on, and some hobbyist readers have the ability to clear codes once the problem is fixed!

If you don't correct the issue, the ECU/SBEC won't start the run cycle count.

Get the codes, get it fixed. We are willing to help. There's also a listing of OBD codes in the "Tech" section of my website - you'll want to go through the OBD-II listing, once you know what your ECU is trying to say.

There's no point in trying to clear the codes until you fix the issues causing the codes. I'm repeating that because it's important.

5-90

AZ Jeff said:

No, you can disconnect your battery for a while and then reconnect it, thereby cancelling the fault codes stored in memory.

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Or, hold in the trip odometer reset while turning the ignition switch from the Off to the On position (not engine start). This will cause the instrument panel to go through its 10 step diagnostics routine and *may* reset the CE light. At least, it has worked on mine.

Dave

It's all moot until the issue causing the code is corrected, tho.

5-90

The number of drive cycles to turn off the MIL lamp, as well as the number of cycles to clear the DTC from computer memory, completely depend on the cause.

For example, after repair of an oxygen sensor high voltage code the lamp will turn off after one drive cycle. I've seen the lamp turn off immediately after replacing the sensor and turning the engine over.

Sounds like I've got to read up on OBD-II again - for some reason, the number "fifty" just stuck in my head.

However, the rest still stands - if you want to get rid of the CEL/MIL, find out what's wrong and fix it!. Othewise, it just won't go away...

Now, where'd I put that OBD-II manual I've got around here...?

5-90

I just glanced at the summary table I was thinking of (from my Equus OBDII manual, its on their site too), and it shows 3 trip cycles, with no faults present of course, to turn off the MIL for most "common" faults (O2 sensors, misfire, and EGR monitors, to name a few) .

I have seen the lamp turn off immediately, however, at least in O2 sensor repairs. This could be because this same table also shows the O2 sensor monitor and heater monitors run once per trip. This sounds conflicting to me, so I'd love to hear some corroborative or conflicting information.

I think those big numbers (50-100 drive cycles) are for the computer completely clearing the DTC once the MIL lamp is off. This same table shows a lot of 40's and 80's for the number of drive cycles to clear the same "common" faults.

Ah.

I'll grant you, I'm not a nuts and bolts OBD guy just yet - I've been focussing on RENIX (since I've got four of those...) I've long thought OBD was overcomplicating system, and OBD-II was worse (and don't even get me started on the proposed OBD-III - an answer in search of a question!)

I do need to dig around on some factory/ASE/SAE literature to bone up on OBD, but I just don't have a reason to at present...

5-90

I did the AZ Jeff trick with the battery; Light went out. Drove 50 mi. and it hasn't come back on yet; if and when it does i'm buying a scanner.

A drive cycle means that the engine is started when completely cold, and then driven enough that it's allowed to heat up to operating temperature before being shut off. It could take as long as a month to complete the 50-100 drive cycles under normal conditions, esp[ecially considering that the engine has to be shut off for about 8 hours or more to be completely cold again.

If you just disco'd the battery and didn't fix anything, chances are you'll be seeing that CEL again. At most, it'll be about a month of regular driving, but I bet it'll come on again in the next 1-3 weeks.

AZ Jeff said:

1. go to the local AutoZone, and ask them to connect an OBD-II scanner to your data bus connector under the dash. This will read the fault codes from your engine control processor that have triggered the light to come on.
2. repair the circuits/elements that are indicated by the codes.

Click to expand...

yes and while doing this,by all means remember you get what you pay for ....autozone how gay.....what if its one of the codes that require real knowledge and real equipment such as a p0420 (catalyst efficiency below threshold) where you need a real scanner to graph the o2 sensors over one another to see if its one of those or the catalytic converter?(not to mention the knowledge to do so) learn the terminoligy of what your talking about before giving advise, i.e. DLC=data link connector pcm= powertrain control module and so on you'll make the poor guy look like a fool..........

Autozone scanning may be uber-ghey, but it's going to be in anyone's price range, and you can then take the code elsewhere (like here!) to find out what's going on and where to look.

If it's simple, you'll be able to figure it out on your own. If it's not, we can tell you where to look for details, or maybe recommend a shop where you can get more info for fair.

Sometimes, you've just got to work with limited resources. This sounds like such a case - take your limited resources (financial/technical/whatever,) and deveop the knowledge to move forward.

At least you'll know some more when you leave than when you walked in - even if it just just a code or two. that can be worked with, can it not?

5-90

as far as I know... You are correct to some extent on the drive cycle. Once the code is cleared, the code is cleared. What a drive cycle is for is when the battery is disconnected or the computer is flashed etc and loses all memory. Here in Pa, you pcm/ecm must have the stored data to get through emmisions or it flags it and automatically fails it. I know there is more to it... But I am just gonna shut up at this point.