Saturday, June 25, 2016

Carprog error: Antena not connected (SOLVED)

Nice!! Hi, all!! Happy to share this for you all, for I just succeeded to solve my Carprog with error Antena not connected.
Days ago, I bought Carprog at from China. I put antena into Carprog clone and choose toyota key, put trannsponder into antena and read ok but i chose transponder vag key show me “antena not connected”.
Ps. Here is the connection diagram, and I connected the device to the power via USB cable. All I did is according to the user manual.

Yesterday I did a little research around transponder section of carprog hardware, because i always got the message – antenna not connected when i tried to read a key with transponder. I found the datasheet for HTRC110 – this is the ic that is responsible for communication with transponders through its antenna. The antenna is a simple coil, and it should form a serial lc circuit with the capacitors soldered on the PCB. The antenna’s inductance (i measured mine) is 283 µH. To form a serial resonant circuit at 125 khz we need a capacitor with approximately 6 nF (i put in my carprog a 7.4 nF because that was what i found). Now my China Carprog clone is reading the transponder (i have only one from my caddy).
Here are the mods i did:
1. replaced 150k with 15k (resistor)
2+3+4 here we need to solder a capacitor with aproximately 6-7 nF(put one or combine from 2-3 capacitors)
5. removed 100 nF capacitor
6. removed 100 pF capacitor
in position 2 it was a 2.8nF capacitor
in pos 3 it was 0.5 nF cap
in pos 4 it was 100 nF cap

Hope this helps you all.


  1. hi do you have a final image about your circuit?

  2. pls if you can writeme