Rant: customer swore his truck 'just needed a sensor' and I spent 2 hours chasing a wiring gremlin
Had a guy roll into my bay off Route 9 in Jersey with a 2012 Duramax throwing a P0087 code, and he kept saying 'it's just the fuel rail sensor, I read it online.' I plugged in my scan tool and watched the rail pressure drop from 26,000 psi down to 4,000 under load, which is not a sensor problem, that's fuel starvation. Turned out a chunk of the return line had been chewed by mice and taped over with electrical tape by somebody who clearly had no clue. Then I popped the tank and found the pickup sock clogged with about a quarter cup of rust flakes and a balled up piece of shop rag. Two hours later the truck runs perfect, no parts replaced except a $14 fuel filter and some new line. Just wish people would stop diagnosing from a forum post before I even pull the dipstick. Anybody else got a go to story for when a customer argues with the scanner results?