The Dreaded 5-Blink Error Code

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Corpus Christi, TX
My Takagi T-K2 finally gave up the ghost (burned up circuit board, which is discontinued) after over 20 years of faithful service I had purchased a T-K4-IN-NG back in 2011 as a spare – this unit was stored in a climate controlled environment and remained in its box until needed. A licensed plumber came out and did the swap.

Now I’m struggling with the dreaded 5 blink / Code 99 error at random times. This usually happens in the middle of washing dishes. Leave the kitchen sink running at hot full blast, everything is fine. Cutting back the hot water a little generates the error on occasion. Reset the unit and everything goes back to working like a champ for a while.

I have not had a chance to check the vent filter yet, but I find it hard to believe that a brand new unit which was installed less than 3 months ago could need that service already. The unit is in the garage, which is fully insulated and is about as clean as a garage can get. The exhaust vent is through the roof and has exactly one elbow, so exhaust flow shouldn’t be a problem. This is the same exhaust pipe and roof vent that was used with the earlier unit.

I am a bit concerned with the original plumber’s use of B vent, which it seems is a no-no for these units. However, as mentioned, the earlier T-K2 worked for decades with this exhaust scheme.

For a plumber, I’m a pretty decent electronic engineer. :) And I’m awfully tired of the occasional cold shower late at night. Does anyone have any suggestions for me?

Finally, is there any kind of hidden menu on the remote to reset this thing? It seems awfully stupid of Takagi to require opening the cover every time! I was not happy to discover that after spending the better part of a hundred dollars on the remote.

Thanks in advance!

John Gayewski

In the Trades
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I'm not sure this brand is popular enough to find someone with enough expertise on it. You'll need to consult the manufacturer.
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