STOP 2P1951 - Caterpillar

Probable Causes
Incorrect information for the password request
Incorrect passwordsRecommended Actions
Check the Information for the Password Request
The information for the password request must be obtained from the Engine Control Module (ECM) that is being programmed. Do not use information from an old ECM in order to program factory passwords on a replacement ECM.Verify that the information used to request the password is identical to the information that is displayed on the Caterpillar Electronic Technician (ET).Engine Serial Number - The engine serial number must be from the Cat ET screen rather than the engine information plate.Reason Code - Use the reason code from the factory password screen. Reason codes are assigned for specific purposes and reason codes are not interchangeable.Turn the key to the OFF position. Then, turn the keyswitch to the ON position. Try to enter the passwords again.Incorrect Passwords
Verify that the correct passwords were entered. Check each character in each password.If rechecking the passwords does not correct the problem, change a customer parameter. Change the parameter from the current value to another value and then change the customer parameter back to the original value. The sequence of events will change the total tattletale. The new total tattletale will require obtaining new factory passwords. Obtain new factory passwords and enter the passwords.