Problem: just before/shortly after starting to heat up, the oven causes the house HFI relay to switch off all power to the house.

(I assume 'HFI relay' is another term for of these: GFCI - Ground Fault Circuit Interrupter, ELCB - Earth Leakage Circuit Breaker, RCD - Residual Current Device, RCCB - Residual Current Circuit Breaker)

I called a professional repair man, and after an inspection he concluded that the main PCB had to be replaced, and adviced me that I was better of buying a new oven. So with nothing to loose, I therefore decided to try repairing it myself.

Featured Document

  1. This particular model is HB76A1560S, but the guide may aply to other. I believe similar ovens are sold under the brand Bosch.
    • This particular model is HB76A1560S, but the guide may aply to other. I believe similar ovens are sold under the brand Bosch.

    • See guidelines in the attached PDF document

    • As per the PDF document: bring the oven into test-mode and start stepping through each menu

    • Identify at which test step the problem occurs and the house HFI relay is triggered

    • (Dangerous!) Remove the backpart, and detach the wires to the heating elements one by one, until the above test step is no longer triggering the HFI relay. Take care to neither cause short circuit nor get yourself electricuted... You probably want to disconnect the oven each time you detach a wire

    • Assuming you now know which circuit that is causing the problem: have a look under the toppart. In my case the problem originated from the control PCB

    • After probing the PCB with a multimeter, I concluded that the relay marked 'B' must be defect. In fact, that realy was visually damaged. It looked like a spark had burned a hole in its plastic housing

    • Order a new relay and solder it in

    • Re-run the test program, and verify that the oven is no longer triggering the HFI relay

    • I did the repair 2 years ago, and it is still working nicely


To reassemble your device, follow these instructions in reverse order.

Attached Documents


Member since: 03/05/2016

101 Reputation

1 Guide authored


I did this repair back in April 2015…. and now again today, 20th May 2018. It was the same part causing problems this time (relay ‘B’ in my document), but since that particular relay was already a used part, I hope the brand new replacement relay will last a bit longer.

LarsWH - Reply

Excellent article LarsWH!

I have this problem with the same control board (4th relay from the left next to ‘C’). I will also attempt the repair and will order a replacement relay. However I cannot get an exact match. I can match ‘HF3FD 009-H3F(576)’ - these appear to be the important codes. However there is a 4 character code at the bottom of the Relay (JI22). I’m not sure if this is important and it’s not mentioned in the PDF attached to your post. Any advice welcome! - Thanks, Jon

Jon - Reply

Thanks a lot Jon :-)

I am pretty sure that the ‘sugear cube relay’ you have found is OK. The additional code is probably just a manufacturing batch code (one of my remaining relays actually says ‘JK36D’…).

Good luck with the reapair and be carefull with that mains stuff.

LarsWH -

Hej Lars

Jeg har også problemer med relæboardet i min Bosch ovn. Trigger hpfi relæet. Jeg har fundet ud af at det er relæ D, det til højre for C ;) Jeg har loddet det ud og nu kører ovnen dog uden undervarme. Men tænker om du måske har et relæ på “lager”. Jeg kan kun finde dem i Kina, men fragt-tiden er jo helt hen i vejret, når man har brug for det nu :)

Og eller tak for et fedt indlæg, havde aldrig fundet fejlen uden din hjælp her!

Mvh. Christian

Christian J - Reply

Hej Christian,

Jeg har stadig 3 relæer liggende, og kan fint sende dig et. Skriv lige en SMS til mig (6171 8242) med din adresse, så kan jeg nok send i morgen (fredag). Brevporto er 9-18kr afhængig af vægt og så koster relæet 15kr.

Jeg er glad for at du kunne bruge min vejledning :-)



LarsWH -

View Statistics:

Past 24 Hours: 3

Past 7 Days: 17

Past 30 Days: 105

All Time: 1,760