BRZ code P000B
 

im looking at buying a brz that has a built motor and turbo on it but the owner says it sometimes throws a P000B code in the summer/ hot weather and apparently only occasionally comes on, the car drives just fine and seems to have no other issues than that when i looked at it and went for a drive in it.

does changing the cam pos sensor usually result in fixing this or does it usually mean the cam gear or timing is off and needs to be fixed?

You say that the BRZ has a "built motor". How far into the motor did the build go? Was it minimal or was it a deep dive? If the position sensor is good and the ECU is set up correctly for the turbo add, then there is a whole laundry list of stuff to look at. I will only add what I know from an experience a friend had and maybe others can add some real case situations. Low oil pressure resulting from an oil pump going bad, but that was not the whole story. The cam timing depends on good oil pressure, so when it got hot, DTCs would show up for Bank 1, Bank 2 or both. Also, partially blocked oil passageways were suspected, but never confirmed. New oil pump and a rebuild of the top end with special attention to the VCT valve body seemed to have solved the problem; no DTCs appeared. However there was one pending code that was somewhat unrelated that came and went several times, but disappeared after a couple of weeks. If I had to put a pin in it, I would have to say that the assembly of the top end of the engine was a little sloppy. But, that is what happens when you are a kitchen table mechanic.

Brand new built map block and fbm stage 2 heads with a jdl gtx3076 gen 2 turbo kit is what it has, apparently 10k ago and are those issues able to be fixed with out tearing the whole motor apart or by pulling the timing cover cleaning it out and redoing it or you think it’s likely deeper into the engine that could be clogged or having issues? Also could you get this code from oil thinning due to not having an oil cooler? Cause I believe it doesn’t have one rn either?

Before assuming that the assembly was faulty or any components are failing prematurely, I would eliminate the cheap and easy stuff first. Coincidently, on two stock engines that friends called me in on, it turned out to be defective camshaft positions sensors, one of which had an overdue recall, or I think it was more like a service bulletin that they act on if one shows up. That is a cheap way of not inspecting every vehicle in a recall, but only fixing the ones that show up in a dealership. Then they act like they are doing you a big favor. Anyway, if you are only getting a DCT from one bank, start with the sensor. The temperature component of this problem is concerning. Low oil pressure affecting the actuation of the cam timing? Can't say for sure sitting in the cheap seats. Here is a little story from a long time ago that while not encouraging an easy outcome for you, but it is illustrative in how to go about attacking a problem. At a dealership that I worked at a Datsun came in with a 1600 engine that needed a complete overhaul due to high miles. I gave the customer the estimate and they brought it in the next day. The idiot dispatcher gave my job to his buddy. I got pissed. Soon I found out that rather than take the engine apart and sub out to the machine shop for the usual stuff, the mechanic talked the customer into going with a short block and then hanging the old stuff on that. Something about that rang a bell. So, I go back and flip through all the service bulletins which apparently I was the only one in the shop who reads them, and found one that warned of a defect in 1600cc blocks. Apparently, a run of engines were put in Datsuns and some were taken out in various stages of completion for warranty and repair work. I kept it to my self saying that it is out of my hands. When the engine was started for the first time it rattled and knocked horrendously. The mechanic was a journeyman and a pro. He went about the diagnostics starting with the obvious and worked his way to getting the engine out and turning over and removing the crankshaft. The oil passages from the main bearing journals to the connecting rod journals were chamfered but not drilled through. The connecting rods were running dry after the pre-lube was gone. When I went over with the rest of the garage mechanics to look at the crankshaft I said, "Damn, now that I see this, I think there was a bulletin that came out." The cars on the production line that had bad engines were discovered and they resolved that. But, bad engines that ended up in the parts supply chain got lost. The bulletin said that if you get a block, pull the pan and at least one bearing cap to verify the crank is good. Bottom line here is that this is the last thing you would expect. Sometimes an engine build can be meticulous, but all it takes is one bad new part. Another quick one that I tell all the time because I got into a shouting match with the factory rep. An MG Midget came in with only a few hundred miles and the clutch would not disengage. I found that the clutch disk was installed backwards. The splined hub is longer on one side, but the extra thick facings from that production run removed any interference until the clutch got broken in. The scoring on the hub was obvious. a new disk is all it needed. The factory dude insisted that my find was impossible, until I showed him the old disk that was saved like every warranty part to avoid this type of hassle from from the factory. I won't go into the details, but then there was the Datsun 240Z that had a defective gear on the camshaft that when assembled at the factory, the overhead camshaft timing was retarded enough so the engine would not go into the upper half of the RPM range. It's a bitch when you do everything you can to get it right, but someone else did not cross the Ts and dot the I's.

Make note of oil temperature and oil pressure (if that reading is available). Anything that can affect the operation of the variable valve timing would result in a DCT. Too bad that there are not more sensors to get a specific fault code. I had a transmission failure on a Mercedes-Benz and because it had all sorts of sensors in it, the exact cause of failure was known. That is better than saying, "It's broke. Just replace the whole thing."