This error code means there may be a communication issue between the ECM and the tuner.
Make sure you pulled the required fuses for your GM vehicle as directed in the tuning process on the device. (See below for reference)
Any aftermarket electronic devices can also impede the download and cause this error.
- Disconnect all aftermarket electronics if you are getting this code, Aftermarket stereos (disconnect and jumper harnesses from the factory harness), aftermarket trailer brake controllers, chargers plugged into the cig. lighter outlets, amplifiers, remote starts, alarms etc. Disconnect anything electronic that didn’t come stock on the vehicle. Low battery voltage is another thing that can cause this error.
- Make sure Battery voltage is at least 12.2 volts with the key in the run position. If it is not, connect a battery charger with 10+amps, or connect some jumper cables to a running vehicle and try to tune the vehicle again.
Replace all Fuses after the Download is Complete!