93 Ford escort has a 172 DTC, what could cause this? on 1993 Ford Escort

HEGO (too lean)

Asked by for the 1993 Ford Escort
Pull PCV Valve and check
PCV Valve operates as it should.....Just checked to be sure. thanks for your response.

Just got back from smog check. I replaced the O2 sensor and cleared the codes. It passed with flying colors, with no Check engine lite.

thanks for the help!