# engine light reset on it's own?



## Snipesy (Dec 7, 2015)

There are various ‘types’ and then exceptions to those types.

I.e. Type A with MIL. Type B, Type C

And those are suppose to correspond to EPA standards.

In reality, they don’t. Like I said there is lots of special exceptions. And GM doesn’t really seem to care about explaining their exceptions.


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## obermd (Mar 3, 2012)

Some codes will clear by themselves. For instance, if you leave your gas cap off the car will set a low pressure evaporative leak code. Putting the gas cap back on will eventually clear this code. Other codes won't clear themselves. What's really annoying is that some codes, such as power steering loss, will degrade the vehicle operation until you clear the code, even if the power steering system is fine.


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## snowwy66 (Nov 5, 2017)

I ran out of gas. I should of had another 30 miles. And I was 2 blocks from maverick. My intended destination. 

After google. It said 10 to 20 cycles. Apparently a cycle is cold to normal operation temp.

I could be 2 to 4 weeks waiting. So I just cleared. See if it comes back.

P0299 and P023F. Fuel pump voltage to high.

When the car died. I hit the button to shut car off. And it went a cranking away. Took a few more button presses before it finally turned off.


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## Ma v e n (Oct 8, 2018)

The control module turns OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warmup cycles, if no malfunctions are reported by this or any other emission related diagnostic.


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## Snipesy (Dec 7, 2015)

You can see the types for each engine platform... I.e. 2017 LE2. Probably all LE2s. OEMs must publish these for EPA standards.



https://gsi.ext.gm.com/gmspo/mode6/pdf/2017/17OBDG03%20Engine%20Diagnostics.pdf



i.e. P023f is type A. 1 trips.

An excerpt from gmw3110 for Tupe A... which costs about $50 if you are really interested...

”The ECU sets the status current, history, and requests illumination of the malfunction indicator lamp (MIL) when the diagnostic runs and fails. The current status is cleared when a Test Pass is reported but the MIL remains illuminated for 3 consecutive ignition cycles, depending on the DTC, when the diagnostic runs and does not fail.”

Useful info? For most things not really. A code is a code.


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## Snipesy (Dec 7, 2015)

To add on... GM doesn’t really tell us when these test conditions occur. Those enable conditions are not something you can see with a scan tool, not even GMs. So it can easilly take 50 drive cycles for a code to clear simply because the test never runs. Some tests require very specific driving conditions which some people just may never reach... Which is an issue that plagues the diesels.


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## snowwy66 (Nov 5, 2017)

According to mavens link. It should have went out with 1 trip.

Guess it's and see now. So far it's still off.


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## BDCCruze (Jul 12, 2017)

You could still run the scan app and look at the status. If it says MIL request and yes or no. If it says No that means the fault is gone but the SES is still active and it's just waiting to clear which should be within a set mileage or drive cycles.


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## snowwy66 (Nov 5, 2017)

Last time I pulled it up. The pending fault was a current fault. P0299. And the historic fault. P023f.

Right now. There's nothing. It's all gone.


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