Hey smart people
. My ranger just got a new clutch, slave cylinder, muffler, tail pipe, power steering hose and a new upper shifter seat
and all of a sudden the CEL comes on after I drive 2 or three miles
. My handy reader gives me a Code 172 HEGO (HO2S) sensor fault/lean. I have heard people saying "check the engine's coolant temperature", which I would, but I have an aftermarket temperature gauge and I tossed the oem sensor. I held on to the oem sensor for a while, but I swapped them out about 5 months ago and haven't had a problem till now. I was wondering if my mechanic might have re-installed the O2 sensor improperly when he was working on the exhaust? I mean, the truck runs fine without it working right, but I really don't like seeing the CEL on. At all. Any help would be much appreciated as I am a less experienced DIYer and I'm hoping it's an easy thing to fix, especially since I will be going back to college this weekend.