P0546 code and 2 blown Turbo's, Pls Help!

Please, any help would be appreciated...

The P0546 Code only pops up on highway and the shafts snapped on 2 turbos while around 3-4K RPM driving on the highway... I'm on my 3rd turbo now (Brand new Subaru OEM Turbo blew less then a month / 1k miles in while babying it) and the car is still throwing a P0546 so I do not want to really drive it further till I figure it out. P0546 states that "Exhaust Gas Temperature Sensor Circuit Malfunction (High Input)".

The only performance upgrade that I have is a SPT cold air intake setup, which has been on the car for over 60K miles. The P0546 code only started popping up a little over a month ago and shortly after the 1st Turbo (original @ 104K miles) blew while on the hwy. The light and code automatically clear while city driving and only come on after driving steady at 2.5K+ RPM driving (such as Highway or open road driving, not racing)...

Also to note the cruise control light flashes when this CEL is on, but that seems to be normal from what I read...

Forgot to Mention, she is a 2005 Legacy 2.5GT 5EAT.

I would just replace the sensor, but I do not think the EGT sensor is causing the turbos to blow up. Am I correct at thinking it is just a temp sensor and if it was just a faulty sensor the turbo wouldn’t be grenading unless something else was at fault, NO?

During both Turbo changes, the shop replaced all the seals, bolts, gaskets... that Subaru recommends while doing a turbo swap.

I have had a shop replace both Banjo bolts and supply line to the turbo.
I also had a shop blow out all the oil supply lines to verify no clogs, verify the coolant lines were clear and flushed the Engines Oil system.

I have checked the timing marks from both the left and right timing belt covers which looked spot on, maybe a half tooth off, but I see that is common for these engines. I was unable to verify the main crank shafts marking while both sides were in alignment, without doing a lot more work which is likely a waste of time...

Does anyone else have any thoughts on what could be causing this?

What kind of fuel are you using?

I have only run 91+ (but usually 93) octance in her since I got it @ 65K Miles. Before that, I can not say what grade they used, but the car has and still does preform great, minus the turbo's blowing suddenly now...

So is the code intermittent???

No, It comes on everytime I hit the Highway, but after a few miles of city driving it turns off... Same code every time...

I would start with pulling your stock catted OEM UP. If the temp. probe is over heating. I'm guessing your cat in your UP is starting to fragment (fail). Under high load it can't flow enough exhaust gas, so it over heats. Cat fragments & very high heat are not good for your turbo.

It's strange your on your 3rd. turbo. You'll thing someone would look at the cat in the UP. It's a place to start.

Mike

It would make sense if that cat is deteriorating and throwing that shaft off when the bits pass through. Could definitely break the shaft if it distorts motion that much. Pull the downpipe, remove the stock up pipe (manifold cross pipe to turbo pipe) and check the cat inside. I'd pick up a cheap sti up pipe for $60 and replace it anyways even if there's no visual deterioration.

If you go with catless UP. Need to remove temp. probe & install 2.2 K Ohm resistor.

http://www.fastwrx.com/p0exgastesec.html

Originally Posted by Subadozer

This is what I have in my notes. According to the last note and in answer to your question it looks like the answer is no.

Replace EGT / O2 Sensor with two 1/2 watt 2.2 OHM resistors
2.2 K ohm, 1/2W. Alternatively, the 1/4W will work, too, if you can find any 1/2 Watt'ers, but there have been past reports from the WRX crowd that the 1/4s burn out sometimes.

Bend the resistor into a "U" shape.

Trace the UP EGT wiring to its proximal end-point, unhook that clip. Insert one end of the "U" into each side of the now-exposed female socket. You'll likely need to trim off a little extra length on the resistor's ends to do so.

Tape in-place securely.

7/8" box wrench may work as an O2 sensor wrench.

A resistor fix is not needed if you get a protune. They should be able to turn off the error.
I have no resistor fix and have no CEL for not having a sensor.

Thanks Guys, Im going to check with the shop I had the Turbo replaced at to see how much it would cost to swap out a up pipe... I searched the web and found some cheaper pipes for STI's but the ones I found for LGT's were more money... Should I stay away from the pipes with flex sections and pay more for a solid pipe, or do the flex ones fit better do to the flexibility off the pipe?

Does anyone know
A) how to check/verify the Up Cat is bad?
and
B) where to get decent Catless up for my motor at a good price?

I would just spend the money on a nice new catless UP and get it done ASAP, but I almost feel like replacing it is just a shot in the dark, one I am willing to take as I am at wits end right now, but a blind shot in the dark none the less. Does anyone know of a good shop in the area that can verify this issue and not Rape me?

Thanks

Just get an STi up pipe. They fit. The OEM sti up pipe works fine. I got mine for $50 shipped used, you can find them here and at Nasioc.com pretty frequently

Would the stock STi Up have a Cat built in, so I wouldn't have to mod (resister) the EGT sensor? Or are the one for Sti's Catless?

STi is Catless UP.

You also need to remove the EGT probe and do the 2.2k ohm resistor from radio shack, tell the guy at the counter you need a 2.2k ohm resistor. he'll give you a package of 5 for $1.25

a tune will take care of that sensor code as well