Member Since: 17 May 2017
Location: London
Posts: 119
Fault code 22 "Reference resistance wrong"
Hi All
I've been trying to diagnose my FBH problem and have read through the huge amount of useful information on here.
I've bought a diagnostic lead from the shop and interrogated the unit via the Webasto Thermo Test software v2.16.1
I am getting the the fault code 22 "Reference resistance wrong". I can clear this code and then try to run the "Manual Heat" option from the Timed Climate screen. The fan/pumps start up but the unit does not fire. I did manage to get it to fire once for a short amount of time by clearing the code, using my IID to prime it and then run with "Manual Heat". There was a bit of smoke and heat from the unit but it only ran for a minute or so before shutting down.
I'm a bit stuck as to where to go next as I've not been able to find much info on this fault code.
Just to add that I cannot seem to get the FBH to start from the Webasto software. The Aux heating/park heating buttons do not try to start the unit. The only way I've managed to get it to start is via the "Manual Heat" button on the Timed Climate screen.
All input gratefully received.
Thanks
Mark
1st Mar 2020 12:04 pm
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18573
Can you get a screenshot of the voltage/temperature/resistance bars in WTT?
I think you've got a faulty glow plug in the Webasto, that's the only thing I think that's measured for a resistance.06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
1st Mar 2020 2:30 pm
spiderlane
Member Since: 17 May 2017
Location: London
Posts: 119
Hi Martin
Thanks for replying. See attached :
Click image to enlarge
Thanks
Mark
1st Mar 2020 2:33 pm
spiderlane
Member Since: 17 May 2017
Location: London
Posts: 119
Just updating this thread with my current thinking.
Looking at the specs for the Webasto TTV it says the cold resistance of the glow plug should be
"At 24 +/- 6°C: 0.200 to 0.300 ohms."
I assume the "Flame Detector" from the diagnostics refers to the glow plug and this is reporting 0.5 ohms (albeit at 9°C), so I'm concluding that the fault code is because this resistance is measuring outside of the expected range.
As I understand it, I cannot buy the glow plug separately but have to buy the whole burner unit?
I think I'll remove the FBH from the car (using a coupler to leave the car usable) and strip it down as per the instructions on here.
Cheers
Mark
Last edited by spiderlane on 9th Mar 2020 10:51 am. Edited 1 time in total
9th Mar 2020 10:45 am
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18573
Sorry Mark I meant to get a reading off my bench TTV, I'll do this and get back to you.06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
9th Mar 2020 10:49 am
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18573
Here we go. Yours at 0.5 ohms does appear to be too high.
06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
9th Mar 2020 10:56 am
spiderlane
Member Since: 17 May 2017
Location: London
Posts: 119
Hi Martin,
Thanks for checking for me.
Interesting. I can see that yours is right in the specified range, so it looks like mine is faulty.
Do you know if I can just get hold of the glow plug? Nearest I've found is part number: LR010329 for the plug and burner unit together.
Cheers
Mark
9th Mar 2020 10:58 am
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18573
No, for the TTV the glow plug isn't a separate part, only in the burner assembly. 06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
9th Mar 2020 11:05 am
alex_pescaru
Member Since: 19 Dec 2010
Location: RO
Posts: 270
A little bit late, sorry, but I am reading this forum only from time to time....
You have over 800 hours of FBH operation, for sure.
It's an embedded/maintenance error for forcing you to service/change the glow plug.
It's a time triggered error, no matter if the glow plug is OK or not.
11th May 2020 4:12 pm
spiderlane
Member Since: 17 May 2017
Location: London
Posts: 119
Hi Alex
Thanks for your reply, much appreciated. It certainly has more than 800 hours of operation (a lot more!).
If I change out the glow plug, how will the unit know that I've done so and clear the code?
I did strip the whole unit down the other week to check and clean out the burner chamber (which was damp with presumably unburned fuel). The resistance then read fine on the bench but upon re-assembly the same fault occurred after I'd primed and tried to run it.
I have cleared the error code many times, but it always comes back
Any guidance you can offer would be very welcome. I have a replacement (used) glow plug I found on eBay but I'm struggling to understand how the unit itself will know that I've changed it - can I reset this internal timer/limit?
Cheers
Mark
11th May 2020 4:22 pm
alex_pescaru
Member Since: 19 Dec 2010
Location: RO
Posts: 270
You need to modify the FBH EEPROM data in order to reset the operating hours.
For that, you need to enter the service/engineering mode of the Webasto Thermo Test program and read the EEPROM dump.
Then modify the dump and then flash it back.
Watch the below video.
Try to autotranslate it, if you are not familiar with the language. (small CC on the lower right, then small sprocket and set it to autotranslate - English)
Also see the other videos and materials in the video's description.
11th May 2020 4:40 pm
spiderlane
Member Since: 17 May 2017
Location: London
Posts: 119
Hi Alex
Thanks for this but I'm afraid I cannot follow it.
However are you seriously saying that all FBHs stop working at 800 hours and need the EEPROM hacking to start working again? There must be thousands of cars with that many operating hours on the FBH - did they all stop working?
Cheers
Mark
24th Jul 2020 2:01 pm
alex_pescaru
Member Since: 19 Dec 2010
Location: RO
Posts: 270
Yep.
And the users either doesn't know the heater is not working anymore - because it's easy to miss it, either they go to a specialized workshop which either change the heater altogether or, if evil, rewrite the eeprom and then say they've changed an expensive part and the user pays the bill... I've seen it happen...
I know it, now you know it, the small family of passionate users know it, but the sum of all LR cars (or heater equipped cars) sold with users that doesn't know it is very big.
So, for them, the above applies, because the manufacturer has no interest to make it public knowledge...
6th Aug 2020 12:27 pm
hotti
Member Since: 22 Feb 2021
Location: Sørøya
Posts: 2
Hey.
we got fault 22 up so we tried to clean everything but still dont work so we baught a new burner with glowplug but we still get fault code 22...
22nd Feb 2021 12:14 pm
spiderlane
Member Since: 17 May 2017
Location: London
Posts: 119
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