When required by this chapter, the owner or operator shall monitor carbon monoxide (CO) exhaust emissions from an affected unit using one or more of the following methods: (1) install, calibrate, maintain, and operate a: (A) continuous emissions monitoring system (CEMS) in accordance with §117.8100(a) or §117.8110(a) of this title (relating to Emission Monitoring System Requirements for Industrial, Commercial, and Institutional Sources; and Emission Monitoring System Requirements for Utility Electric Generation Sources), as applicable; or (B) predictive emissions monitoring system (PEMS) in accordance with §117.8100(b) or §117.8110(b) of this title, as applicable; or (2) sample CO as follows: (A) with a portable analyzer (or 40 Code of Federal Regulations (CFR) Part 60, Appendix A reference method test apparatus) after manual combustion tuning or manual burner adjustments conducted for the purpose of minimizing nitrogen oxides (NOX ) emissions whenever, following such manual changes, either of the following occur: (i) NOX emissions are sampled with a portable analyzer or 40 CFR Part 60, Appendix A reference method test apparatus; or (ii) the resulting NOX emissions measured by CEMS or predicted by PEMS are lower than levels when CO emissions data was previously gathered; and (B) sample CO emissions using the test methods and procedures of 40 CFR Part 60 in conjunction with any relative accuracy test audit of the NOX and diluent analyzer.