Engine codes. P0128, P0522

[WingdwheeL]

Ok, brand new to forum. Just bought an 04. It has a Good amount of performance done. After few days, oil light comes on then off. Day later... Service Engine light. Pulled codes and got P0128 (coolent thermostat) and P0522 (oil pressure sensor/switch). I read though some older threads and got some good info. I figured I would replace pressure sensor switch and do fresh oil (change (Mobil1 0w-40 sounded like that was a popular choice for a decent moded SRT). Would that be accurate statement?
Do you think this should fix and prevent future P0522? Or should I also think about replacing oil preassure sending unit?
As far as the P0128... I do not know what type of thermostat is currently installed. Since i purchased the car a few days ago The aftermarket temp gauge has been reading just under 150 all the time. I thought that seemed a bit low?When car idles for a while temp rises 160/165ish. The Water temp gauge is also reading around 150. Should I buy new thermostat and radiator cap? A 180 degree?

[TenZen]

Define performance done. Change oil pressure sending unit. I suppose changing the thermostat and cap while you're at it. No idea about the oil. I've been using Mobil 1 5W-30 since I bought it. Only way I know to prevent a p0522 is to change the oil pressure sending unit.

[WingdwheeL]

Here is a list of known upgrades: probably missed a few things but that should at least give u a good idea.
AGP Big Turbo kit with Garrett 50 trim.
Tial Wastegate with Dump tube.
Walbro 255 fuel pump
1200cc injectors
AEM Cold air Intake
MagnaFlow 3" Turbo back exhaust
4" intake
ACT Clutch Kit
3 bar map/tip sensors.
Apexi Turbo Timer
Maddog 72 Reduce Short Throw Shifter
MPX front mount intercooler
55mm throttle body
Ported intake to match throttle body
HKS blow off valve
Tuned by JMB inc

So u say you would replace sending unit and not to bother with the pressure sensor? Also... Since the car has been custom tuned what if I replace thermostat to 180 and it has like 160 installed? Is that going to affect tune????
The only reason I think there might be 160 is cuz the temp never gets much higher then that. thanks for the response!

[TenZen]

Sending unit/pressure sensor is the same thing. I don't know much about tunes, I would just ask whoever tuned it about the t-stat and cap. I would guess it uses the same cap as stock. I remember reading that these cars like to to run hot, and unless it's been tuned to run as low as it does, the PCM will run in closed loop (I think). Meaning it will run like its trying to warm up. I'm assuming it's been tuned to run with like that though, so I wouldn't worry about it.

[Maddog]

PCM needs to see 180F before running in closed loop. If you are continuously running under 180, PCM will probably stay in open loop or bounce back and forth. This will normally cause it to run much richer, although I'm not 100% sure on that. These cars ran rich from the factory, but not sure what Justin did for that on the tune.

This is what I'd do:
#1 - change your oil sending/sensor unit - that's not something you want to mess around with.
#2 - while you're under there, change your oil to Mobil 1 5W-30, or the High Mileage variant if you're over 75k. Use an Delco PF13 oil filter - it has a much larger media exposure which means more oil flow through the filter, which in turn will give you better filtration.
#3 - as TenZen said, change your t-stat and cap. Stant makes a good cap, and try to get a t-stat made in USA, Canada, or Israel (yes, Israel). T-stat could be sticking open, or cap could be bleeding off pressure.
#4 - change your coolant temp sensor
#5 - reset PCM with a 30 minute battery disconnect