This article explains the meaning and how to address the syslog message "kernel: tcbc i2c accelerator error: Read failed for (FPD1)"

The I2C primary initiates all communication on the I2C bus and supplies the clock for all backup devices. If there is an issue with the I2C backup, it disrupts communication with the I2C bus and the device ID. These logs can be present for different components such as the CB, FPM, FPC, etc.., Data is disrupted on the FRU component and it fails to populate the show chassis hardware details. The chassisd will identify the failed FRU component in the log messages. Mentioned below are logs seen when the Front Panel Module [DPM or FPD - Front Panel Display] is encountering i2c error:

Jan 10 06:07:31 router kernel: tcbc i2c accelerator error: Read failed for (FPD1) group 0x2a device 0x54 bytes 1 err 5

Jan 10 06:07:33 router chassisd[12845]: CHASSISD_I2CS_READBACK_ERROR: Readback error from I2C slave for FPM 0 ([0x2a, 0x21] -> 0x0) 

i2c access has a retry mechanism, so depending on the frequency of i2c error following actions are suggested:

1. A single i2c error indicates a transient i2c issue between RE and corresponding FRU and can be ignored
2. For persist i2c error on FPM, reseat FPM module to fix connectivity issues Document on FPM reseat
3. If the error persists, perform a RE SO and verify
4. If the error persists even after RE SO then, replace FPM module
5. Contact Juniper TAC if you need assistance