Quarq DZero - Failure After Dropped Chain?

Background: Have a Quarq DZero/SRAM Red22 crankset

Towards the latter part of my ride this morning, my chain dropped as I was shifting from small to big ring and got stuck between the small ring and the frame. Fortunately, I was going slow and managed to pull over and fix it.

After a mile or two, I noticed the power reading (3 sec avg) displayed on my Garmin 830 was way off. It was reading very low power for a mid to high effort, ranging from 0 to 50W.

I pulled over again to recalibrate it through the Garmin. Got an offset of ~450. Rode again for another few miles and the same issue. Pulled over, took out the battery and put it back in, then recalibrated. This time, an offset of ~570. Went a few miles again and had the same issue. Cadence reads perfectly fine. ​

Did some quick research and it seems this is a relatively common issue based on some SlowTwitch and TR threads. But others have been getting really high (or low) offsets of -32000 and even some have their max power measurement pegged at 2400W.

To further diagnose, I’m going to try the following in order: Calibrate using SRAM AXS app (seems to have replaced the Qalvin app), reinstall and retorque all the fasteners holding the spider to the crank, contact SRAM/Quarq. Unfortunately for the last one, I purchased my unit secondhand and warranty has likely expired at this point.

Anyone else have the following issues and have found or can suggest a fix?

Thanks in advance

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I had the same thing happen, sent it back to Quarq as it was toast, luckily still under warranty.

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Weird! I remember the Quarq I had years ago did this. Would register 2000-3000 watts when chain dropped. But it never went dead. It would go back to normal once the chain was back on.

I set my current Quarq so that I don’t ever drop chain so not sure if it’s still the case. Hope it gets resolved!

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I had the same thing happen to me. The chain dropped into the BB. Stopped, reset the chain, and kept riding. My Quarq DZero first started showing absurd numbers (around 2-3kw), and after a while, it would just show zero. Unfortunately, I bought my PM second hand and it was out of warranty, so Quarq could not do anything for me :confused:
Got another one though because I really like the PM, as long as it worked it was really reliable but I did install a chain catcher to avoid that issue in the future - I’m sorry but I think this can not be fixed.

Thanks everyone for your input.

I reached out to Quarq support and they were helpful. Basically nothing could be done since it’s out of warranty and I’m not the original owner. However, they offered great deals on a crank + power meter packages. I ended up just buying another Quarq DZero Dub spider from a separate dealer anyways since they were running a sale, so all is well now! I heard this failure mode is now fixed on newer Quarq DZero spiders?

Same thing happened to me a little over a year ago. Known issue. There was a thread on slowtwitch. I was lucky to be in warranty still.

Quarq’s have been awesome when I’ve static weight tested them for accuracy. But I’ll think hard next time I need to buy a new one.