how much off does the speedo need to be before they warranty it?

[949]

so im curious how off does the speedo need to be off for them to fix the issue?
and also correct the mileage that the difference has created?

[Blue Smoke]

No exactly an answer to you question but according to one report, car manufactures volunteer to meet the guidelines per SAE (Society of Automotive Engineers) J1226, which is +/-2% or -1%/+3% on a sliding scale at low speeds or -0%/+4% above 55 mph.

Separately, the USDOT states the manufacturer's speedometer must be within 5 mph of actual at 50 mph (+/-10%).