I just replaced my Thermostat housing due to it failing
now car is in limp mode (the 1/2 yellow engine light is on) for whatever reason.
car is completly stock,and runs great!the only code I pulled prior to thermostat housing replacement was the code for that housing,(it was not opening) I cleared the code then proceded with job removing and reinstalling it. all the electrical plugs are in their correct sensors,hoses are also all conected properly in their right spots.
84,000 on the odometer and I just recently within the last 1000 miles replaced all spark plugs with NGK,and all new delphi coil packs,and decarb the valves,so they are clean,I have no T-chain rattle,coolant level seems fine,oil level is good! the only thing is the cooling fans have not come on since refilling the coolant ,but its pretty cool today in the 70s I have bleed the system (I think) and seems to be running cool about 180 degrese at the top and bottom radiator hoses. I have disconected the battery for 15min to clear the ECU and that 1/2 amber yellow engine light still comes on imedatiely after start up. what am I missing here? please help shed light,my gut feeling is there is still air in the coolant system,but when I unscrew the the bleeder valve I get a steady stream of coolant coming out of the bleeder valve with no bubles.
the light was not on prior to thermostat replacement only the check engine light

 

 

all vacuum lines are conected

 

 

So this is where I am at ,over the weekend after posting this thread the car finally thew a code P0460 01 ( fuel pump level sender In gas tank) after replacing the thermostat it threw the 1/2 engine power yellow amber light on my odometer only with still no check engine light, and no code so I decided to hook up my obd2 and after several start ups and hours latter it finally kicked out that code,so I was like great I guess things happen in pairs,when the Original thermostat took a dump my car was down to 2 red carrots on the gas guage, this was back in july of this year,so the car sat over the hot summer with virtually no gas in it,I did however start it a few times before tackling the job of the thermostat.. when I did this job I pulled the intake to get to the water pipe that bridges between the water pump and the t-stat housing,way easier, because but it broke apparently at the waterpump side when taking the t- housing out but could not see that it was cracked because it cracked around the flange where it inserts into the backside of the water pump,I only found that crack because it leaked after filling the system up,so everthing had to come back apart to replace that pipe.The second time I replaced that pipe it came with with a new rubber O ring seal however it got pinched,when inserting that new pipe and seal back into the back side of waterpump,and I greased the heck out of it,had to pull it out,fustrated at this point I just reused the old rubber seal becuse it will still soft from the old water pipe but guess what? it leaked so I tore it all back apart again! everytime I did this job I pulled the intake off to get to that waterpipe.point being just like you mentioned there was sensor that was not making cotact posibly,all sensors were pluged in and locked but some of the wires on all were bent 90 degese so I straightend the wire out,wiggled them around on all the plugs then put it back together.
I then proceded with clearing all the codes,took car for a drive and all seems good so far,car seems to run normal.wether or not the fuel pump is going bad that remains to be seen,but since I ran the gas so low it was down to probably a 1/2 gallon or less when that limp mode light turned on and then poping the code for the fuel pump level sender, so I wonder if having the very low gas caused the limp mode light to turn on,and being that the foat on the level sender was probably all the way down not floating in gas caused that light to pop? anyways we will see
or having taken the intake manifold off several times jogged a wire loose,time will tell.
thanks guys for your input

 

 

It was a total nightmare,I will give this advise if anybody is planing to replace that water pipe,do not try to push the pipe straight into the backside of the waterpump,the seal may roll and get pinched,the 2 times I installed the pipe it got pinched,the first time I could see it sticking out but it was to late,I had already put it all back together and filled the system,the second time it got piched on the water pump impeller side so the water pump ate the seal then leaked,could not see it. instead,slightly put it in at a angle closest to the engine block as you slide it in,it's pretty tough so use a good grease intended for rubber seals not wheel bearing grease.also remove intake manifold makes life way easier,but be sure to check all electrcal conections and make sure none of the wires are jogged or bent over tight,one last thing for r56 models,make sure that when you do install the water pipe there are 2 vacuum lines one is a hard plastic the other is rubber they can get piched in beteween the the block and the waterpipe pinching off vacuum,and you can not see it unless you are aware of it ,it"s a bear to pull them out,so pay attention and make sure those lines are on the opposit side of the pipe so they do not get piched like mine did! you will thank me latter.

 

Gotta change the thermostat on my R55 this week. Just started seeing steam rise from the hood at the windshield and it's throwing the thermostat code. Other than changing the water pump pipe, what else should I look forward to replacing when doing this? I don't want to have to tear into it again for a while.

 

buy a new pipe even if you think it is ok.good luck