I’m driving my wife’s 2002 VW Golf on the highway to build miles (it’s at 84k). It’s a manual with gearing that’s at 3500 rpm at 70 mph in 5th gear, which seems pretty high. It had been doing fine on the highway, even though the RPM seems a bit high due to gearing, but it keeps me under 80 mph (highway is largely 70 mph). It burns oil, but not too bad, like a quart every 500 miles or so.
Recently, when driving at “high” speed (slightly over or near 70 mph), I get a plume of intense white smoke. After slowing down, the plume goes away, and I can continue near 65 mph.
After this happened today, I put on a code reader, and saw of P0159, air fuel ratio oxygen sensor issue.
Any ideas on what causes the white plume of smoke, and what to do about it? Seems like the car should have more miles on it.