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BOSCH Tankless T9800SE 160K BTU shows C1 & C2 error

hi, I have BOSCH Tankless T9800SE 160K BTU showing C1 & C2 errors. Intake pipe distand 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 couple of days.


  • tester22
    tester22 Member Posts: 50

  • GGross
    GGross Member Posts: 1,050
    "I did Auto Tuning of this Machine to adjust Air & Gas pressure automatically"

    While there are machines that can self tune combustion, if you are getting error codes related to combustion you still need to know the numbers. I am also going to call BS on Bosch manual here, as they don't show anywhere that they have a sort of gas-adaptive or lambda pro system, they just claim the unit is "pre-adjusted from factory" which you cannot do without a gas-adaptive or lambda pro type system because the unit doesn't know what type of venting it is attached to. I have to believe if this auto-tuning function were similar to the others mentioned Bosch would give it a name and market on that the same as the others do.

    So what I am getting at, is to just consider that maybe the feature on the unit designed to be sold to homeowners to self install who don't know better, might not be working correctly and should at the very least be checked manually.