Knowledge/Fault finding/How to read a fault code before you look it up
How to read a fault code before you look it up
Every brand shows its codes differently. Some count lamp flashes, with a second lamp changing the meaning. Some show a four-character code two characters at a time. Some spell out a five-character word instead of a number. Some use long pulses for the category and short ones for the cause. Know your brand's method and you'll get the code.
- Flashes plus a second lamp
- 3 brandsActronAir, GENERAL (formerly Fujitsu), Mitsubishi Heavy
- Alternating halves
- Samsungtwo-character display, four-character code
- Words, not numbers
- Temperzonefive-character words
- Long then short pulses
- Brivis, Bonairecategory then cause
How does each brand show its codes?
| Brand | How the code is displayed |
|---|---|
| ActronAir, GENERAL (formerly Fujitsu), Mitsubishi Heavy | Count the flashes on the indoor lamp. The state of a second lamp changes what the count means. |
| Samsung | A two-character display that shows a four-character code in two halves, one after the other. |
| Temperzone | Five-character words, not numbers. |
| Brivis | Digits on the Networker wall controller. There's also a green LED flash code on the HCDSI24-1DT board. Long pulses give the lockout category and short pulses the specific cause. Up to 12 flashes, repeating every 4.8 seconds. |
| Seeley, Braemar, Breezair | A tri-colour LED flash count on the electronics module, or the code on the MagIQtouch controller. |
| Daikin | Digits on the wired controller. On a wireless remote, an inspection mode with an LED and beep pattern. |
| Mitsubishi Electric | A code on the remote controller, plus red LEDs on the outdoor circuit board. Solid red means an operating state, flashing red means a fault. On K-control units, read outdoor LEDs LD1 to LD8. |
| Rinnai | Scrolling text on the display, with the fault code and a phone number to call. |
What's the tens-and-units trick on gas heater boards?
Braemar and Seeley gas heater boards use two LEDs as tens and units. Every green flash on the PWR LED counts 10, and every red flash on the HT LED counts 1. The red FLT LED shows the lockout condition.
So one green flash and eight red is FC18. Not FC1 and FC8, and not FC9. If you don't know the convention, you'll misread that board every time.
The evaporative side has its own version. If the top LED is double flashing green, everything is OK. That's normal operation, not a two-flash fault. Good to know before you go looking for a problem that isn't there.
Why learn the display method before the meaning?
Almost every fault code page on the internet is a table of codes and meanings. Very few explain how to read the code in the first place. That's the bit that stalls you at a wall unit with no manual.
It's also the bit that doesn't date. Code meanings change between model families and firmware versions. The way a brand displays its codes tends to stay the same across the range.
Once you've got the code, go to the manufacturer's own current list for the meaning. Match the exact model and the electronics fitted, because on several brands the same number means different things on different product lines.
Had a fault that didn't make sense?
The ones worth talking about are the ones where the code pointed one way and the cause turned out to be somewhere else entirely.
Send it through. If enough people have hit the same thing it becomes a page.
Who this is for: small and medium HVAC contractors in Victoria. If you're a homeowner after a rebate or a repair, you need a licensed contractor, not us, and yours can point you the right way.
Related
- Daikin fault codes: how they're built, and where to look them up107 codes in a grid, a letter for the part of the system and a digit for the detail. How to read it, and the seven meanings we could confirm.
- Which brands publish their fault codes, and which don'tSome manufacturers put the whole service library online with no login. Others publish nothing you can actually open. That changes how long a fault takes.
- Reading Braemar ICS fault codes off the board LEDsGreen flashes count tens, red flashes count ones. Plus the three lockout levels, the service PIN, and the order of checks that finds the real cause.
- Most overheat faults are airflow, not gasBrivis codes 40 to 43 and 53, and Braemar FC10 and FC19, most often come down to restricted airflow. Here's the order I'd check it in.
Review date: 1 April 2027. Figures in this area change without much notice and this page carries some that will go stale. Every number above is dated and sourced so you can check it yourself. If you find something out of date here, tell us and we will fix it.