Get error code E037. I have tried to go through

You might have set an amount limit accidentally. Check your programming manual for codes to set amount limit (sometimes high amount lock out or HALO) and set it to none (or on some models just set it to zero to deactivate it). If it is just affecting one PLU, try printing out the PLU programming and see how that PLUs settings are different from the others

Yes, you have accidentally set a payment limit when you were programming it. I can't remember the exact code for that model. You could try the standard Casio limit removal:

Key on program mode
0
Cash
Subtotal

It sounds like an entry limit has been set. This is often called HALO (high amount lock out) in many manuals. Look in your programming manual to see if there is a limit function. If you need a programming manual, one of the users has most of them here:
https://the-checkout-tech.com/

It happens when someone accidentally re-programs the cash button while trying to change prices because they are not following the pricing instructions correctly. Try programming the cash button as a zero price. Do it just like you are making a price change but enter zero into the cash button instead of an item.
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For those who have asked about a programming manual for the PCRT500, one of the users has it here:
https://the-checkout-tech.com/manuals/cashregisters/Casio_PCR-T500_PCR-T520_Operation_and_programming_manual.html

You have a digit limit set on the cash button. It has been programmed to allow only a small amount to be paid via cash. You need to look up the codes for digit limit (HALO) in your manual and it will guide you through the processes for setting a digit limit on the cash button. If you have lost the manual, one of the users has one listed here:
Casio PCR T500 PCR T520 Operation and programming manual PDF

Remove the digit limit. Theres a code in the manual somewhere to remove limit on cash key

Error E037 is a high amount lock out/low digit lock out error. So you're probably entering an amount that is over the high amount limit. The manual can be found here: http://parklandbm.com/downloads/CASIO%20TE-900%20Operators%20Manual.pdf

For the steps to change the high amount limit, see page 31 of the manual. See also page 32 for an example of the high amount limitation.

Someone has programmed a limit on the CASH button. Try this:
Turn key to program position 0 CASH SUBTOTAL 3 SUBTOTAL 0 CASH SUBTOTAL
Turn key back to REG mode and try it.
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If anyone needs a Casio PCR-T470 manual, head over to C-tech: http://the-checkout-tech.com/manuals/cashregisters/Casio_PCR-T470_users_and_programming_manual.html

sounds like an amount limitation on the cash key.

try turning the key to program, pressing 3 subtotal, 0 cash, subtotal to clear any amount limitation on that key

It sounds like you have a lock out high amount limitation.

email me so I can send you a picture that will explain it more. My email is [email protected]

In the subject put the Eo37 error code so I know it it from you. The picture explains it, I will try to explain it since it will not let me paste a picture on here. On one of the programming keys it has been programmed (came that way, or accidentally done) that locks the register if a certain limitation of amont of money has been totaled. In your case $30.00. The manual should show or tell you how to unprogram or change the high amount limitation.