• Code: 7244
• Description: Broken developer thermistor Y wire
  The sensor input sampling is greater than 230.
• Remedy: Developer thermistor Y: 1. Confirm Developing is displayed by U139 temperature and humidity. 2. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit Y and Front PWB (YC15) Front PWB (YC2) and Engine PWB (YC10) 3. If the wiring is disconnected, shorted or grounded, replace the wiring. 4. Replace the Developer unit Y.
  Front PWB: Replace the front PWB.
  Engine PWB: 1. Check the engine software and upgrade to the latest, if necessary. 2. Replace the engine PWB.

• Code: 7251
• Description: Short-circuited developer thermistor K
  The sensor input sampling is less than 69.
• Remedy: Developer thermistor K: 1. Confirm Developing is displayed by U139 temperature and humidity. 2. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit K and Front PWB (YC9) Front PWB (YC2) and Engine PWB (YC10) 3. If the wiring is disconnected, shorted or grounded, replace the wiring. 4. Replace the Developer unit K.
  Front PWB: Replace the front PWB.
  Engine PWB: 1. Check the engine software and upgrade to the latest, if necessary. 2. Replace the engine PWB.

• Code: 7252
• Description: Short-circuited developer thermistor C
  The sensor input sampling is less than 69.
• Remedy: Developer thermistor C: 1. Confirm Developing is displayed by U139 temperature and humidity. 2. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit C and Front PWB (YC13) Front PWB (YC2) and Engine PWB (YC10) 3. If the wiring is disconnected, shorted or grounded, replace the wiring. 4. Replace the Developer unit C.
  Front PWB: Replace the front
  PWB.Engine: PWB 1. Check the engine software and upgrade to the latest, if necessary. 2. Replace the engine PWB.

• Code: 7253
• Description: Short-circuited developer thermistor M:The sensor input sampling is less than 69.
• Remedy: Developer thermistor M: 1. Confirm Developing is displayed by U139 temperature and humidity. 2. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit M and Front PWB (YC11) Front PWB (YC2) and Engine PWB (YC10) 3. If the wiring is disconnected, shorted or grounded, replace the wiring. 4. Replace the Developer unit M:

• Code: 7254
• Description: Short-circuited developer thermistor Y wire
  The sensor input sampling is less than 69.
• Remedy: Developer thermistor Y: 1. Confirm Developing is displayed by U139 temperature and humidity. 2. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit Y and Front PWB (YC15) Front PWB (YC2) and Engine PWB (YC10) 3. If the wiring is disconnected, shorted or grounded, replace the wiring. 4. Replace the Developer unit Y.
  Front PWB: Replace the front PWB.
  Engine PWB 1. Check the engine software and upgrade to the latest, if necessary. 2. Replace the engine PWB.

• Code: 7401
• Description: Developer unit K type mismatch error
  Improper adaptation of the machine and developer unit K is detected.
• Remedy: Different type of the developer unit is installed: Install the developer unit of the correct type.
  Developer unit K: 1. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit K and Front PWB (YC9) Front PWB (YC2) and Engine PWB (YC10) 2. If the wiring is disconnected, shorted or grounded, replace the wiring.

• Code: 7402
• Description: Developer unit C type mismatch error
  Improper adaptation of the machine and developer unit C is detected.
• Remedy: Different type of the developer unit is installed: Install the developer unit of the correct type.
  Developer unit C: 1. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit C and Front PWB (YC13) Front PWB (YC2) and Engine PWB (YC10) 2. If the wiring is disconnected, shorted or grounded, replace the wiring.

• Code: 7403
• Description: Developer unit M type mismatch error
  Improper adaptation of the machine and developer unit M is detected.
• Remedy: Different type of the developer unit is installed: Install the developer unit of the correct type.
  Developer unit M: 1. Confirm that the wiring connector is firmly connected and, if necessary, connect the connector all the way in. Developer unit M and Front PWB (YC11) Front PWB (YC2) and Engine PWB (YC10) 2. If the wiring is disconnected, shorted or grounded, replace the wiring.