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

  3. Thanks for helping! It's really work.

  4. Hi! I've tried your way to fix and yes is real. But still have problem . Carprog say transponder signal too low. If you know how to fix it ill be verry happy. Thanks