Description: Broken outer thermistor wire The sensor input sampling is greater than the reference value. (After detection, controlled at 25 °C/77.0 °F)
Remedy: Temperature sensor 1. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Outer temperature sensor and Main/Engine PWB (YC24) 2. If the wiring is disconnected, short-circuited or has ground fault, replace the wire. 3. Replace the temperature sensor PWB. Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the Main/Engine PWB.
Code: 7901
Description: Drum unit K EEPROM error No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated 5 times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
Remedy: Drum unit K 1. Unplug the power cord from the wall outlet, and wait five seconds. Then plug the power cord and then turn on the power switch. 2. Confirm that the connector of the drum unit is firmly connected, and if necessary, push the unit all the way in. 3. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit and Drum relay PWB (YC2) Drum relay PWB (YC1) and Main/Engine PWB (YC15) 4. If the wire is disconnected, short-circuited or has ground fault, or the connector pin is deformed, replace the wire. 5. Replace the drum unit. Drum relay PWB Replace the drum relay PWB. Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the Main/Engine PWB.
Code: 7902
Description: Drum unit C EEPROM error No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated 5 times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
Remedy: Drum unit C 1. Unplug the power cord from the wall outlet, and wait five seconds. Then plug the power cord and then turn on the power switch. 2. Confirm that the connector of the drum unit is firmly connected, and if necessary, push the unit all the way in. 3. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit and Drum relay PWB (YC4) Drum relay PWB (YC1) and Main/Engine PWB (YC15) 4. If the wire is disconnected, short-circuited or has ground fault, or the connector pin is deformed, replace the wire. 5. Replace the drum unit. Drum relay PWB Replace the drum relay PWB. Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the Main/Engine PWB.
Code: 7903
Description: Drum unit M EEPROM error No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated 5 times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
Remedy: Drum unit M 1. Unplug the power cord from the wall outlet, and wait five seconds. Then plug the power cord and then turn on the power switch. 2. Confirm that the connector of the drum unit is firmly connected, and if necessary, push the unit all the way in. 3. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit and Drum relay PWB (YC3) Drum relay PWB (YC1) and Main/Engine PWB (YC15) 4. If the wire is disconnected, short-circuited or has ground fault, or the connector pin is deformed, replace the wire. 5. Replace the drum unit. Drum relay PWB Replace the drum relay PWB. Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the Main/Engine PWB.
Code: 7904
Description: Drum unit Y EEPROM error No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated 5 times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
Remedy: Drum unit Y 1. Unplug the power cord from the wall outlet, and wait five seconds. Then plug the power cord and then turn on the power switch. 2. Confirm that the connector of the drum unit is firmly connected, and if necessary, push the unit all the way in. 3. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Drum unit and Drum relay PWB (YC5) Drum relay PWB (YC1) and Main/Engine PWB (YC15) 4. If the wire is disconnected, short-circuited or has ground fault, or the connector pin is deformed, replace the wire. 5. Replace the drum unit. Drum relay PWB Replace the drum relay PWB. Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the Main/Engine PWB.
Code: 7911
Description: Developer unit K EEPROM error No response is issued from the device in reading/writing for 5 ms or more and this problem is repeated 5 times successively. Mismatch of reading data from two locations occurs 8 times successively. Mismatch between writing data and reading data occurs 8 times successively.
Remedy: Developer unit K 1. Unplug the power cord from the wall outlet, and wait five seconds. Then plug the power cord and then turn on the power switch. 2. Confirm that the connector of the developer unit is firmly connected, and if necessary, push the unit all the way in. 3. Confirm that the wiring connector is firmly connected, and if necessary, connect the connector all the way in. Developer unit and Drum relay PWB (YC6) Drum relay PWB (YC1) and Main/Engine PWB (YC15) 4. If the wire is disconnected, short-circuited or has ground fault, or the connector pin is deformed, replace the wire. 5. Replace the developer unit. Drum relay PWB Replace the drum relay PWB. Main/Engine PWB 1. Check the engine firmware and upgrade to the latest version if necessary. 2. Replace the Main/Engine PWB.