08 vw touareg v10 TDI extended crank

I have a 2008 vw touareg that has an extended crank issue.
No codes, rpm over 600, noticed a -90 degree Celsius reading in 01 engine, measuring block 98, 4th group, group had the coolant temp - can not find any info out on this vehicle, owner said it is one of 85 that are in the country with a v10 TDI in that year.
No fuel pressure ports to access on the rail.
Checked batteries - both failed and were dated 07', replaced batteries, did hard reboot, cleared codes, vehicle starts fine now but after test drive cranked over a little longer then before test drive, have feeling it will be back.

What is this group 098 reading? That -90 Celsius sticks out to me. Any info would be great

That could be for a sensor that isn't installed if the entire vehicle is fault free. It is also possible that another temp sensor that's really installed and wired to another controller (Tranny/ATF, IAT or something like Ambient Air temp. for example) is malfunctioning. If that vehicle comes back run and save a complete Auto-Scan so you can post the results.

I didn't dig into the repair manual but that vehicle would use one, if not two, electric fuel pumps so checking pressure/volume and the fuel filter couldn't hurt.

-90 strikes me as rather unusual; most of the time an open-circuit temp sensor reports something in the -40 to -50 range..

-Uwe-

Scanner showing 7.5 bar as fuel pressure, no test ports on the rail to tap into like Mitchell says.

I have the original scan at work, I'll post up on monday