Couple of years ago I purchased a glowshift wideband afr kit.
Great little toy. Bosch 4.9 sensor, module, harnesses and gauge.
About 8 months ago the readings starting showing 20 afr and flashing but I know it wasn't lean.
It flashes when it becomes too lean.
If the bosch sensor is faulty the gauge shows an error number. Not the case.
I just bought a new module (60 USD) and still the same error.
I have some pinholes in the exhaust manifold so I'm now suspecting it's fresh air getting into the exhaust before the lambda and giving me the false extreme lean conditions.
I do need a new manifold, probably next month.
Cross-over or standard I'm not sure yet.
Hopefully the new manifold will solve the issue and I'll be able to see my afr readings again.
Now I have a spare datalogging module!!