I had my toyato rav4 of 2009 my cd plyer shows error3

https://www.zemiceurope.com/media/Documentation/A12(E)(OC).pdf

OL is OverLoad, you need to recalibrate

ERROR 3
The zero point is out of range when turning on. Please make sure no load is on the scale when turning on.

..

Most likely an hardware issue. ( Faulty player)

could be viewing lens or something stuck in the cd

google this error code

The easiest way is to buy a a wireing adapter that connects up to your original factory harness for your factory radio.There will be instuctions with it. Showing you what wires to connect up to the kenwood deck. You can get them at wallmart,Or most audio stores that sell car audio.

two reasons why CD/DVD players will not read
1. the optical lens is bad
2. the motor is not spinning at the correct rpm

try to find a rewritable media that is compatible with your player, like it can read recorded dvd disc . some dvd plyer dont have capable of reading photo cd, recorded disc, burned disc etc. maybe your player is the one like that.

Error 3.CD error message.
The pick-up is out of focus during play mode due to scratches on the disc or contamination.

This can be a disc format error (try a previously known working disc)
Or the laser may be out of alignment. - in this case professional repair/cleaning/alignment is recommended.

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Quite a few players from that time did not play mp3's, due to the format's relatively new status. There is no way to play mp3 if the player didn't originally support it. You can try taking the mp3 discs you have and "up convert" to WAV type, then play them on your unit...accordianman