No power just cadence !!!

Try removing the battery caps and install them again. However ONLY TIGHTEN BY HAND and be very careful. The threading is very soft and you don't want to smash it!

But removing the battery caps resets the pedals (to my knowing)...

Will register 40+W if I go flat out otherwise it reads 0 or something <15W. Have tried 2x 510 head units, a 920xt and Fenix 5 as well as GC on iPhone, same results.

Your readings are consistent with having an uncorrected zero offset. Did you do a manual calibration from the Edge or the watches? The auto-zero process will not succeed when there is a large correction required - this prevents 'nuisance' errors on the offset.

Removing and replacing the batteries does not affect the zero settings on the pedal either way - it does not clear them, and it does not cause them to get re-computed when the batteries go back in.

Thanks, Have finally sorted it out. My head unit was trying to get me to calibrate install vector angles and pedal between 80-90rpm. Could do this for 10 minutes with nothing happening. Managed to skip that stage and manually calibrate. Have a power reading that within 10w of my trainer.

Hi I have a problem too. Brand new installation and the power reading is completely wrong. I have installed the pedals and updated the firmware using the mobile app. I have tried to calibrate from my 810 and it does not work. I have set the power angle at 50% on the app. How do I get the power reading correct? At the moment it is either super low or super high. Is there any other way to calibrate other than use the 810 as sits asking me to cycle at 80-90 rpm?

as the OP said, bypass the autozero pedaling thing that the 810 is asking you to do and just do a manual calibration. There should be no pedaling or inputting of settings required. I would also not mess with the power angle, leave it at whatever the default setting was or 0.

I have tried to calibrate from my 810 and it does not work.
...
Is there any other way to calibrate other than use the 810 as sits asking me to cycle at 80-90 rpm?

What software version is your 810 at?

I have the same problem as OP. my vector 3s are showing correct cadence but no power. I am using a Wahoo Elemnt head unit. Don't have a Garmin head unit.
Is there software in the Garmin headunit to do a calibration of the pedals.
Im not sure if the pedals are simply broken, or I need to zero-offset via a Garmin.
Can this calibration be done via Garmin connect or Garmin express app.

Thanks

Im not sure if the pedals are simply broken, or I need to zero-offset via a Garmin.

did you do a zero offset from the Elemnt? If so, did it return any kind of status code?

I didn't do any zero offset at all. I was (maybe wrongly) under the impression that the unit automatically does a zero offset.
Im not sure how to do the zero offset on Wahoo. I assume it is thru the app on the phone as there is no apparent facility on the head unit for this.

See https://support.wahoofitness.com/hc/en-us/articles/115000382484-How-do-I-Calibrate-a-Power-Meter-with-the-ELEMNT-

Follow these steps to calibrate your power meter:

• Wake up your power meter.
  
• Press the Menu button on the left side of the ELEMNT.
  
• Use the Down button on the right side of the ELEMNT to scroll to your paired power meter.
  
• Press the Left button to select "Calib".
  
• At this point, the ELEMNT has sent the command and you will need to follow the calibration procedure specific to your power meter.
  
• The ELEMNT will notify you when calibration is complete.