I know there are a bunch of threads about E05 errors in these heaters but I just went through this whole exercise and what I discovered might help someone else. My E05 error started about 3 weeks ago. I swapped the SFS out, cleaned all the Crud out of the heater and put it back together. Still got the E05 error. Pulled the exhaust flue off to check for blockage - it was clear. I toned out all the wiring with a meter and found no issues. Checked the thermistor and high cutoffs. Both ok. Figured it was the board so my maintenance guy let me borrow an old board he had. I installed his board and the heater worked fine for ten mins until I shut it down manually.
I took my board to my workbench and checked it out under a big magnifying glass to see if I could spot bad solder joints, failed components etc.. I discovered the traces along the bottom edge of the board that connected to one of the SFS header pins had corroded so there was no continuity between the pin and the through-way the trace connected to. I soldered a jumper wire between the two points and reinstalled the board. Voila! Working heater and I saved the cost of a new board.
For giggles, I checked the borrowed board. Yep, same corrosion and it looks like it'll fail sooner than later so I'm going run a jumper on that board as a "thank you".
Pics show the problem and my fix. The "gunk" in the closeup is the board's conformal coating coming off. The borrowed board shows very similar damage.
I took my board to my workbench and checked it out under a big magnifying glass to see if I could spot bad solder joints, failed components etc.. I discovered the traces along the bottom edge of the board that connected to one of the SFS header pins had corroded so there was no continuity between the pin and the through-way the trace connected to. I soldered a jumper wire between the two points and reinstalled the board. Voila! Working heater and I saved the cost of a new board.
For giggles, I checked the borrowed board. Yep, same corrosion and it looks like it'll fail sooner than later so I'm going run a jumper on that board as a "thank you".
Pics show the problem and my fix. The "gunk" in the closeup is the board's conformal coating coming off. The borrowed board shows very similar damage.
