I am new to the GM Forum. Please If I am posting something in the wrong place or something that has been addressed before- point me in the right direction. At the moment I am working on a 2011 GMC Duramax LML 6.6 L Diesel. This truck has been nothing short of a nightmare. I keep getting an annoying P0088 Fuel rail pressure to high. It only seems to be happening on start up. I have a slight amount of knock from the fuel system until pressure goes down. I am monitoring the fuel rail pressure desired and actual when the problem happens. Seems as though briefly actual is way higher then desired in a 10 second window. Example actual is 11,000 and desired is 5000 and after a moment the actual matches the desired. This vehicle has no other symptoms. Drives good has no performance issues. I have been around in circles with this thing. Anyone seen anything similar to this? We have done pretty much everything we can think of and still having problems. this one has me stumped. Any help would be appreciated. thnx

Aaron

I've heard the fuel pressure regulator can fail and cause the this problem. Also, could be a bad injector or two. A friend told me you can tell a bad injector by scanning the exhaust manifolds with an IR temperature scanner. The cooler spot on the exhaust manifold corresponds with the bad injector.

Never worked on diesel myself, so afraid I can't help beyond that.