Junkers Bosch
Fault Codes

Listed below are the common Junkers Bosch fault codes as described by the boiler manufacturer along with a possible cause.

Junkers Eurostar Error Codes

Error A3 The flue gas sensor has a fault or a short circuit. Check sensor and cable and replace if necessary.

Error A4 Exhaust gas outlet through the flue gas box. Check the chimney.

Error A7 Open circuit in the NTC sensor circuit for hot water supply. Check sensor and cable.

AC error A gap between the TA 211E or RAM and the control unit. Check the cable.

Error b1 The coding plug is not recognized by the electronic board. Correctly install the plug, replace if necessary.

CC error Outside temperature sensor circuit of TA 211E block has a break. Check the outdoor sensor and cable.

Error d1 The return voltage from the LSM does not come. 5. Check the LSM 5 circuit for the flue gas valve.

Error E0 Internal fault on the electronic board. Replace the electronic board.

Error E2 Open or short circuit in the NTC sensor circuit of the direct pipeline. Check cable and NTC sensor, replace if necessary.

Error E9 The maximum temperature limiter has tripped. Check the NTC flow sensor, pump, and fuses on the electronic board.

Error EA No ionisation current. Check inlet gas pressure, power supply, ignition electrode with cable, and ionization electrode with cable.

A7 The hot water temperature sensor is defective.

A9 The hot water temperature sensor is not installed correctly.

C4 Differential pressure switch in non-operating position does not open.

C6 The differential pressure switch is not closed.

CC Outside temperature sensor not detected.

E2 The flow temperature sensor does not work.

E 9 The limiter in the flow line has tripped.

EA No flame detected.

F0 Internal fault.

F7 Although the appliance is switched off, a flame is detected.

FA A flame was detected after the gas supply was cut off.

Error F7 Incorrect ionization signal. Check the ionisation electrode with the cable for damage.

FA Error The ionisation current remains after the regulators have been switched off. Check the gas fitting.