Since I got my X5 in May, with a 1/4 tank in it, I've never let the tank go below 1/2 full. My first drive was to the gas station where I filled it with 93 octane. I've topped it up twice since then, in late October before the state inspection, and in December, to get some "winter gas" in it.

I've only put <400 miles on it since I got it; about 200 before the first codes appeared in early November, after the inspection, and the rest of the miles since then, along with repetitive codes. At no time did it get below 1/2 tank.

However, I have seen the SES light pop up just after I've made a hard right turn (3 times, at the same intersection where I have to avoid getting rear-ended), and once more when I made a hard left acceleration onto the freeway, avoiding an idiot that tried to enter in front of me from a side street. Is the fuel moving away from the siphon pump pickup?, or is something else in the tank associated with the codes?

The freeze frames I've recorded show info that corresponds with those incidents; I use Torque Pro full-time on my dash-mounted spare Android phone to monitor my fuel trims to see if anything goes haywire, but the trims stay pretty consistent, close to the reported freeze frame info. They're always a bit high, but I don't know what other X5's with M54 engines get for fuel trim readings.

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01 BMW X5 E53,3.0i-5L40E, 7/13/01
topas-blau,Leder-grau,"resto-project car"

Here:
14 Lexus ES350,3.5L-U660E
09 HHR Panel,2.2L-4T45E
04 Chevy 2500HD,6.0L-4L80E
98 GMC Sierra 1500,5.7L-4L60E

Gone:
66 Chevelle Malibu 2dr ht.,327>441c.i.-TH350>PGlide/transbrake
08 Cobalt Coupe,2.2L-4T45E
69 & 75 C10s,350c.i.-TH350
86 S10,2.8L-700R4
73 Volvo 142,2.0L-MT4
72 & 73 VW SuperBeetles,1.6l-MT4
64 VW,1.2l-MT4
67 Dodge Monaco 500 2dr ht.,383c.i.-A727
56 Chevy 210 4dr,265c.i.-PGlide