: P2261 Check Engine Light Help: Supercharger By-Pass Valve Stuck Help, anyone else?

06-11-11, 01:35 AM
Hello all,

Since I had my V tuned by jesse @ wait4me, I've thrown a P2261 code, usually comes back a few minutes after resetting it. The code is refered to as "Supercharger By-Pass Valve Stuck" but by searching on the interweb, I've also seen results of "P2261 - Turbo/Super Charger Bypass Valve - Mechanical"

originally I thought it was because the vacuum line was pinched under the supercharger. I replaced that line, and I'm still getting it. I look at the by-pass valve while revving the engine, and it appears to be moving up and down properly.

So my question is if anyone else has had this issue before. Is it because I'm running more boost with a smaller pulley? Has anyone upgraded their bypass valve? I see there is a Dejon Bypass Valve, "Boost fooler" or other aftermarkets. Factory replacement is $120. Do I need an aftermarket one, or should I try factory again?

Thanks in advance for any help.

P.S. Also i found this, but I dont know if it applies:

#06-06-04-053: LC3 Engine MIL/SES, DTCs P0128,
P0171, P0174 or P2261 (Reprogram ECM) - (Oct 16,

Subject: LC3 Engine MIL/SES, DTCs P0128, P0171, P0174 or P2261
(Reprogram ECM)
Models: 2006 Cadillac STS-V, XLR-V
with Supercharged 4.4L NorthstarŽ DOHC V8 SC Engine (VIN
D -- RPO LC3)

Some customers may comment on an illumination of the SES/MIL with no other symptoms. Upon
further investigation, the technician may find one or more of the following DTCs stored in the ECM:
This condition may be caused by a calibration issue that causes DTCs to set when no fault is
If routine diagnosis using SI does not reveal any obvious cause for the DTCs setting, reprogram the
Reprogram the ECM with the latest calibrations if the above concern is encountered. An updated
ECM calibration is now available to address this concern. This calibration, or any that follow, is
designed to address this concern. Refer to Service Programming System (SPS) using the
appropriate Service Information (SI) procedures.

06-11-11, 09:34 AM
That is just saying there is a dealer update available for fix that problem via software flash. Do you have a handheld? If so, i can just apply that update to your current software you are running in the car. Simple.

As for what it is complaining about though is that little black box thing that wiring plugs into. It is saying that it isnt getting a signal from that little black box.

06-11-11, 10:58 AM
I dont have a handheld. =(. I do have a Tech2 at the shop however.

Is that little black box the actual bypass valve that has the metal rod going into it? That looks like a hat almost?

As always, thanks for your help jesse.