EC2X issues. Sporadically dropping sat fix and returning CME 516 error

Subject of the issue

Sporadically the GPS radio decides to stop fixing and starts returning the following error
{ "reason": "516", "type" : "CME" }

Your environment

AutoPi Telematics Unit Pi3
version: 2021.07.12
running without 4G sim card

Steps to reproduce

Tell us how to reproduce this issue.
Leave the unit powered on (with power_timer sleep events disabled/cleared)
Power cycling the unit sometimes fixes the issue, sometimes it does not. There are no clear/consistent ways to resolve this except to keep unplugging and then replugging the unit into the OBD port

Expected behaviour

the GPS should stay on and should lose fix as long as there are sats available

Actual behaviour

the GPS reports being on, but returns no satellites in fix stats and throws error described above

Output of power.status command

rpi:
  uptime:
    days: 0
    seconds: 25705
    since_iso: '2021-07-22T13:10:30.211815'
    since_t: 1626959430
    time: '7:8'
    users: 1
spm:
  current_state: 'on'
  last_state:
    down: none
    up: 'on'
  last_trigger:
    down: none
    up: spm
  sleep_interval: 0
  version: '2.2'
stn:
  battery:
    level: 100
    state: charging
    voltage: 13.7
  last_trigger:
    sleep: NONE
    wake: NONE
  trigger_config:
    ext_sleep: '  LOW FOR 3000 ms'
    ext_wake: '  HIGH FOR 500 ms'
    uart_sleep: '  900 s'
    vchg_wake: '  +0.50V IN 1000 ms'
    vl_sleep: '  <12.20V FOR 240 s'
    vl_wake: '  >13.20V FOR 3 s'

Do’s & dont’s

  • Do not write your unit-id anywhere.