If the receiving device detects a parity or CRC error in the incoming sequence it responds with negative ACK/NACK per SPMI standard.

If the transmitting device sees NACK response, it tries to resend the message as many times as indicated by SPMI_RETRY_LIMIT register bits. After that it considers the SPMI bus inoperable, sets SPMI_ERR_INT interrupt and goes to the safe recovery state and executes an orderly shutdown. Bus arbitration requests do not count as failed attempts if a target device loses bus arbitration. SPMI_RETRY_LIMIT counter is reset after each successful transmission by the device.

If a target device has determined that SPMI does not work reliably it does not respond to any SPMI commands anymore until power-on-reset event has occurred. This "no-response" behavior is to prevent continued operation in a situation where SPMI is unreliable. If a target device does no longer respond to any SPMI command, the controller device on the SPMI bus detects a missing target device on the network during the periodic testing of SPMI bus. The target device then internally handles the SPMI error condition per error handling rules set for the device (in general executing an orderly shutdown). SPMI block signals to the device that SPMI bus error has occurred after the retry limit has been exceeded.