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Discussion Starter · #1 ·
Hey guys,

When my key is in the ignition and on the second click (“on position”) I notice my check engine light stays on and doesn’t go away. It only goes away once I start the engine. Is this normal behavior?

(see pics below)

Vehicle Gauge Car Speedometer Auto part
Gauge Measuring instrument Speedometer Tachometer Auto part
 

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The Bacon Hauler (‘12 Cop Charger)
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Yes it’s normal.

It’s also a way to tell when all the emissions monitors have run and set to Ready (meaning your can safely get it inspected after a recent battery unhook).

If the CEL blinks and then stays illuminated after several blinks, it’s ready for inspection. If it blinks and then goes out (iirc), it’s not ready for inspection yet.
 

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2018 Scat Pack SHAKER in Plum Crazy- GONE :-(
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Also, ignition is on and a TON of stuff is wrong, like O2 reading, Oil Pressure, basically that is a "It ain't running right" light, and since it is not actually running, is a valid cause!
 
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2020 Dodge Challenger Hellraisin Scat Pack
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Yep. Was explained to me that it is the way the system is designed. The CEL is fed common power like all (or most) warning lights. It takes specific action on the part of the engine controller -- or in the case of the airbag light the airbag controller -- to extinguish the light. This by setting an I/O pin high -- which is upon power on is low. Setting the I/O pin high breaks the ground path of the light and causes the light to go out.

This is in some way a fail safe circuit. It has to be actively interacted with to turn off the light. If this interaction fails for whatever reason -- in my experience an airbag light that the ground control pin from an I/O chip was no longer operational -- the light stays on.

The tech tried a new airbag controller. The light stayed on. The tech then borrowed -- with the owner's permission -- an instrument cluster from another car and when this cluster was connected to my car and the key turned on the airbag light went out. I "fixed" the always on airbag light by buying a used instrument cluster.
 

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Discussion Starter · #6 ·
Yes it’s normal.

It’s also a way to tell when all the emissions monitors have run and set to Ready (meaning your can safely get it inspected after a recent battery unhook).

If the CEL blinks and then stays illuminated after several blinks, it’s ready for inspection. If it blinks and then goes out (iirc), it’s not ready for inspection yet.

I didn't notice at first, but I just saw that the CEL blinks several times before it remains illuminated. This is when the key is turned to the "on position (2nd position)". So the blinking is normal behavior, yeah?
 

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The Bacon Hauler (‘12 Cop Charger)
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I didn't notice at first, but I just saw that the CEL blinks several times before it remains illuminated. This is when the key is turned to the "on position (2nd position)". So the blinking is normal behavior, yeah?
Yes, when blinking it is doing its own check of the various emissions monitors. Once it's checked them all, it will either remain lit or go out. If it goes out, the monitors have not all run or one (or more) has failed. If it remains lit, all of the monitors have passed, and the vehicle can be taken for a state inspection without fear of being failed for "Not Ready" status.

This is an easy way to know when you are good to go for an inspection if you do not have an ODB2 scanner to help read the monitors' readiness state.
 
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