BOSCH Tankless T9800SE 160K BTU shows C1 & C2 error

[tester22]

hi,
I have BOSCH Tankless T9800SE 160K BTU showing C1 & C2 errors. Intake pipe distanc is 39 foot & Outlet pipe distance is 43 foot, I am having this Machine from last 5 years working fine, but from last couple on months showing this errors. So I did many thing, but none fix the problem, as follow below.

1--I did Camera inspection in Intake & Outlet pipes all clear (not any debris shows).
2--I did Air Filter Clean & Water Filter clean, all clear now.
3--I did DESCALING of Machine.
4--I did Auto Tuning of this Machine to adjust Air & Gas pressure automatically.

After many different things still showing C1 & C2 errors, some time in a week and some time in


When I unplug & replug Machine, at that time at the beginning it will show SOLAR on display (Solar blinking on display for few minutes, after that it will disappear), so what its mean by SOLAR.

 

[kj_mustang]

From the install manual: Display reads SOLAR but without existence of solar thermal system. Power demand lower than appliance minimum output power. ▶ Increase hot water flow
Probably just a temporary reading while the system is starting up. The C errors are the ones to worry about.
Did you reset the error by holding the On/Off button for 3 seconds?

 

[Jackfre]

I haven’t spent time with the Bosch line, but have seen problems at the inducer motor wheel on other brands. The vent is clear as you have determined. Look at the fan blades and the outlet to the burner to ensure that they too are clear.

 

[tester22]

Yes all the time i press power button for 3 sec to reset the error, some time comes this error 3 or 4 times in a day.

But beginning of this error started once in a month, later twice in a month, then later once in a week, now is more worst.

And yes I remove the Fan and Clean the Blades, but Burner is too deep inside the Machine, need to open full machine to clean upper level etc.

 

[Jackfre]

Make sure you have a complete gasket set prior to going into the burner.