will 171.2C put my truck out of service
No. Across our inspection records, code 171.2C has never resulted in an out-of-service citation—0% OOS rate all-time. Of the 2 citations in our database for this violation, both were issued with the truck remaining in service. Compare that to the FMCSR average OOS rate of 31.4%, and you're looking at a violation that FMCSA does not classify as a roadside removal offense.