Inactive or stored codes are things that have happened in the past but are not currently a problem. Active codes are things that turn on the check engine light and are wrong now.
Could be in need of a tune up. If the "check engine" light is or has illuminated, have it scanned for codes first. The codes will help lead you to the problem.
Could be a restriction in the exhaust such as a catalytic converter that has had a meltdown. If the check engine light is or has illuminated, check the codes.
Could be many reasons. Assuming the check engine light is on, start with having the codes that are set read. That will help lead you to the cause.
You did not say what year it is. In general you can get an OBD reader that plugs into the port on the car and use that to reset the codes by erasing them, OR you can pull the fuse on the ECM or you can disconnect the battery. If the light does not go out when any of these are done then the issue that made the light come on is not corrected.
Have vehicle scanned and codes cleared - usually a problem in the emission control system
My rpm light came on but not my check engine light so what does that mean when the rpm light is on
Stop by AutoZone and ask them to use their code reader because officially they are not allowed to reset trouble codes.
get your engin checked get your engin checked battery disconect for 3 min or take to auto parts and they can do it
same problem.
Have vehicle scanned to determine the problem
you check the system for trouble codes.
To check engine light codes one would have to bring your vehicle to a mechanic who can use a computer to check the computer chip that regulates this function.
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Auto Zone will check your engine light codes for FREE...
Evap Emmissions system has small leak PO442
It requires a scanner to properly diagnosis a check engine light.