This fault code usually relates to a problem with the CPIM module.
A number of factors can be at play when this fault code appears by itself:
1. CPIM could have a hardware fault.
2. CPIM could have water ingress or water damage (corrosion).
Remedies
1. Send the CPIM back to EQSS for troubleshooting/repair.
2. Open the main CPIM cover and check for water ingress and/or PCB corrosion. If water damage is found then open an EQSS support request - then send the CPIM back to EQSS for troubleshooting/repair.
When this fault code occurs in combination with other fault codes:
1. Check the CAN bus cable and CAN bus jack for signs of damage (check CAN bus cable continuity if possible with some sort of continuity tester).
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We don't encourage customers to open the CPIM as that action may compromise the water seal integrity of that unit.
2. However, as a last resort, unscrew the CPIM cover and check all of the internal PCB connectors (re-seat connectors onto terminals if necessary). The CPIM cover - rubber gasket seal - must then be carefully re-seated before firmly screwing down the CPIM lid (for continued CPIM module water ingress protection).