P0246 - At a loss

[ImprezaJoe]

My 03 wrx threw a P0246 a while back causing it to boost to wastegate pressure but no more. On this forum I read some older posts by a guy named Broxma who had the same issue and determined it was the switching mechanism in his ecu that shorted. He fixed it by replacing the ecu. Well I replaced my ecu with another 03 wrx ecu and now this one has thrown a P0246 code. I've checked and double checked the wiring to my 3 port ebcs (mac valve) and determined that is not the problem. I've also used a multimeter to check voltages (and referenced Broxma's thread to make sure I've got the right numbers) and everything checked out. I'm at a loss. My car seems to be eating ecu's and I can't seem to figure out the short.

Has anyone else had experience with this CEL?

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[Charlie-III]

Did the issues start when the new valve was installed?
If yes, maybe the wiring is wrong.
If no, check the wiring to see if it has a short in it.

Sounds like a wiring issue or short that is taking out ECU's.

[ImprezaJoe]

I used this thread as a reference:https://forums.nasioc.com/forums/sho....php?t=1346749

The issue appeared before I wired in my 3 port ebcs. I bought the 3 port thinking my stock bcs was shot but it turns out that wasn't the case. I stumbled upon the referenced thread and purchased another ecu to fix the problem (2/21/17). That worked fine until recently when it threw the same code. I bought a 3rd ecu and installed it yesterday, but immediately threw the code upon hitting boost. Car still boosts to wastegate 7 psi. I know for a fact it is an electrical issue because I overboost to the moon if I unplug the vac hose to the wastegate.

My thoughts are that I've got a short between the BCS and the ecu that is making it return a much higher voltage than what is "acceptable" to the ecu. I think that is the cause of my 3 fried ecus. I checked the power wire (yellow/blue) to the BCS and found the reading to be about 12.3-12.5 volts with the key in the ON position.

I tried to run the ground from the BCS to a chassis ground without using the ecu ground wire but it threw the p0246 code upon turning the car on (before I even drive or hit boost). I'm no EE but I think that means the ECU is looking for a return voltage to either enable or disable the BCS.

I'll be chasing the ground wire this weekend to determine if my issue is grounding related. Because of all the headache this issue has given me I plan to continue documenting my tests/findings and hopefully post a final solution to this code.

Joe

[jagreenleaf]

Any update on this? I've got a p0246 code in my 04 wrx. I know the solenoid is good, took it out and tested it(can blow through it when it has power, resistance is 32 ohms). Getting 12 V to the power wire(yellow and blue) and around 4 V to the wire that goes to the ECU. I checked and I'm also getting 4 volts at the ECU pin. This is in test mode. I've tried another ECU and the exact same thing happens. I've reset both multiple times and as soon as I go into boost that dreaded code comes back. No idea what to do at this point besides getting a MBC.

[ImprezaJoe]

Originally Posted by jagreenleaf

Any update on this? I've got a p0246 code in my 04 wrx. I know the solenoid is good, took it out and tested it(can blow through it when it has power, resistance is 32 ohms). Getting 12 V to the power wire(yellow and blue) and around 4 V to the wire that goes to the ECU. I checked and I'm also getting 4 volts at the ECU pin. This is in test mode. I've tried another ECU and the exact same thing happens. I've reset both multiple times and as soon as I go into boost that dreaded code comes back. No idea what to do at this point besides getting a MBC.

I was sitting in my shop shooting the **** with some buddies about my one off problem way back when and thought to Google the old post. Well here I am to finally respond.

It's the wiring to your ebcs, there's a short or break somewhere. I was dumb in 2017 and disregarded the first answer because I thought I checked everything. Rerun your wiring clean and toss a new ECU in. Go hit boost.

God my car has changed since then