3.0 SCV6 P0089 code - anyone got a fault finding process to follow?

[Pagoda]

I have a 2016 SCV6 with around 65K miles. Runs perfectly well; no performance issues, but the CEL has come on. The only relevant code showing on the IID is P0089-64 (EC) fuel pressure regulator performance, etc,. When cleared it reappears within 30 mins or so of normal driving, but has also cleared itself from time to time.

Digging around quite a bit on the internet it seems the LP FP in the fuel tank could be the culprit, but before I embark on ordering a new unit to the tune of ~$300, plus what looks like an unpleasant job dropping the tank, I wanted to ask if anyone had advice on proper diagnostics/steps to take to properly identify the fault. (I read about a software update, and I can give that a go with the help of GAP but I don’t hold much hope it’ll have much of an effect. The vehicle had the recall for the fuel tank gasket done a good year or so back; they may have updated the software then but I have no idea).

Given that there’s no performance impact I’m tempted to leave it and see what happens but grateful for any advice/pointers.

Cheers.

 

[16FujiDisco]

Search P0089-64 and there are several threads discussing. I believe the general consensus is in-tank fuel pump, but there is also a tsb for a software update. I get the code anytime temps are below 40 degrees, but no other time; no performance issues

 

[ClevelandLR4]

So I had p0089-64,p008A-07. Ran perfect, no misfire,no start issues. Dealer and my scanner can’t find anything wrong, code came and disappeared three time with engine light. Dealer thought may be low pressure pump going out. I changed that my self. Code went away for three and a half months. Then same code came back. Again all reading on scanner for sensors looked fine to me and dealer both, suv runs perfect but engine light was on. So dealer said Hail Mary passs- start replacing things. They suggested low pressure sensor ( passenger side ,near cross membrane, next to transmission bell house) as first t replaced. But on you tube there is excellent diagnostic video by opus IVS( 1 hr 22 min long). Expert said do fuel control module ( or fuel program drive module- Fpdm) change first as low pressure sensor is hardly at fail in his experience. It is very easy to remove trim driver side trunk area ( see powerfuluk video about it).I replaced fpdm and codes r gone. Feels like vehicle is running smoother too( didn’t have misfire before). Make sure to remove battery before u unplug fpdm and plug in new one. Fpdm in lr4 2015 driver side trunk trim removed as below in photo. Loosen 3 silver 8 mm bolts to slightly move ac components out of the way and behind duct fpdm sits, very intuitive.
Software update was already done few years back .

 

[Pagoda]

Thanks for this. What's the part number of the part you replaced please?