e60 is a generic heating issue
without going into diagnostics its difficult to be exact
e61 – Heater unit faulty. Wiring faulty. NTC sensor
incorrectly calibrated/out of position. Electronic
board faulty.
e62 – Heater unit faulty. Wiring faulty. Electronic board
faulty.
e63 – Thermostat faulty (replace heater unit). Heater unit
faulty. Wiring faulty. Electronic board faulty.
take your pick… but if its intermittant, its more likeley a pcb issue
do you clean your condenser regularly?