Having problems with your 2001 Hyundai Accent ?

P1805 eeprom/vin missmatch - 2001 Hyundai Accent

Posted / edited by AnonymousUser on : 26-10-2020

Answers :

Hi there,

P1805 means Immobilizer EEPROM Error -\012

The Immobilizer Control System (ICS) is an anti-theft device that enables starting to be possible only when the mechnical and wireless secret code (memorized in the ECM and SMARTRA), are aligned simultaneously. The transponder (built -in the ignition key head) sends a unique frequency code signal to the SMARTRA (SMARt TRansponder Antenna).

The vehicle immobilizer system consists of the ECM, the SMARTRA and ignition keys with built-in TRANSPONDER. -


The ECM carries out a check of the ignition key using a special encryption algorithm, which is programmed into the transponder as well as the ECM simultaneously. Only if the results are equal can the engine be started. The data of all transponders, which are valid for the vehicle, are stored in the ECM.

The SMARTRA carries out communication with the built - in transponder in the ignition key. This wireless communication runs on RF (Radio frequency of 125 kHz). The SMARTRA is mounted at the ignition lock close to the antenna coil for RF transmission and receiving. The RF signal from the transponder, received by the antenna coil, is converted into messages for serial communication by the SMARTRA device. And, the received messages from the ECM are converted into an RF signal, which is transmitted to the transponder by the antenna.
The SMARTRA does not carry out the validity check of the transponder or the calculation of encryption algorithm. This device is only an advanced interface, which converts the RF data flow of the transponder into serial communication to the ECM and vice versa.

(built-in keys)
The transponder has an advanced encryption algorithm. During the key teaching procedure, the transponder will be programmed with vehicle specific data. The vehicle specific data are written into the transponder memory. The write procedure is once only ; therefore, the contents of the transponder can never be modified or changed.

Repair Help & Product Troubleshooting for 2001 Hyundai Accent

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