There is a TSB that addresses this concern which should be performed first.
TSB-2023-035-E-R3
Warranty for 8 years from the date of sale.
If the error is still present:
Issue
P0606 and P0605 indicate a power or communication issue with the ECU. When these codes occur, the tractor may crank over but not start, and Diagmaster may not connect to the machine.
Solution
Before completing the below steps, refer to TSB-2023-035-E. If the problem persists after completing this bulletin, refer to the steps below.
1. Clear the codes from the intellipanel (refer to Mode b in the WSM). If the codes return, proceed to step 2.
2. Inspect the engine ECU connector for any moisture, corrosion, or other damage to the wiring or pins. Check that all pins in the engine ECU connector are tight and in place. Check for bent or backed out pins, or broken off wires where they go into the connector. Pay close attention to pin 50 on the engine ECU connector (red wire). Make sure it is secure and tight in the connector and no corrosion is present. If inspection reveals no abnormalities, proceed to step 3.
3. Plug the engine ECU connector back in, and with the key on, check for battery voltage on pins 4, 6, and 71 of the engine ECU connector. Voltage should be approximately battery voltage.
4. With engine ECU connector plugged in, check voltage at pin 50. With the key on, voltage should be less than 1 V. With the key off, voltage should be approximately battery voltage.
5. Remove the engine ECU connector and check continuity to frame ground from pins 1 and 2 of the ECU connector. Resistance should be less than 1 ohm.
6. If all of the above tests are within spec, this indicates a faulty ECU.