Bosch Condens 2000 W - Detailed Error Troubleshooting

8 | Failures / Errors
3.3 Failure codes and corrections steps
A2 and operating LED is flashing.
Combustion chamber NTC failure (behind burner) : when the temperature by CC NTC reached to limit
1)
Control Step Action
1. Check if combustion chamber NTC dam-
aged or not and the position.
B Switch off the appliance.
B Pull the NTC cables out.
B Measure NTC resistance.
Are the values correct ? (see NTC val-
ues)
yes: B Check the cable connection.
A2 failure still exist ? -->2.
no: B Change the NTC.
B Connect the cable.
B Switch on the appliance.
A2 failure still exist ? -->2.
2. Check if cable damaged or not.
B Switch off the appliance.
B In case of NTC is cahnged :
- Pull the NTC cables out.
- Measure NTC resistance.
- Reconnect the NTC cable.
B Pull out the 20 poled connector on
control unit.
B Measure the NTC resistance directly
on 20 poled connector. Are the meas-
ured values on NTC and cocnector dif-
ferent ?
yes: B Change the cable harness.
B Switch on the appliance.
A2 failure still exist ? -->3.
no: -->3.
3. Is there any blockage on flue gas pipe? yes: B Remove the blockage.
A2 failure still exist ? -->4.
no: -->4.
4. Is the correct MAP (fan speed) value
according flue gas pipe length choosen ?
no: B Adjust correct MAP value according flue gas pipe
length and diameter. See capitel 7.2.
A2 failure still exist ? -->5.
yes: -->5.
5. Is fan running correct ? no: B Change the fan.
A2 failure still exist ? -->6.
yes: -->6.