Mdelfunt
Member
Hey all, this forum has always been helpful to me and I wanted to share a problem I found today on my 05 Jetta. I was getting intermittent Low boost codes and limp mode. I had changed my Turbo actuator a few months ago and thought it might be something associated with that. When testing vacuum at the Turbo actuator with vacuum gauge, at times I would have 20"hg and other times I would get nothing.
I used VAGCOM to cycle N75 and I would get vacuum at times, and other times I would not. I thought N75 might be bad but I was losing vacuum at the supply side. However, I had consistent vacuum from the pump that never faltered. It was almost like a solenoid valve was cutting on and off which is what made me think N75 might be the issue.
I noticed that when pinching the hose going to the vacuum reservoir on the valve cover the vacuum would go to normal. Investigating further, it turned out that the rectangle door in the valve cover that covers the reservoir was leaking around the edge. I didn't even know it was a cover until this (see picture below). Most diagrams show the vacuum reservoir as a round plastic ball. My understanding is that at some point, VW replaced the ball with this little compartment inside the valve cover. For some reason, they put this little cover on the top and it apparently comes unsealed. I read another contributor on the forum suggesting the same thing.
I took a large screwdriver and gently snapped the cover off all the way around it (you could break this thing if not careful). I then mixed some epoxy and glued the cover around the entire parameter.This solved my Under boost /Limp issues. Just wanted to share in case this helps someone in the future.
I used VAGCOM to cycle N75 and I would get vacuum at times, and other times I would not. I thought N75 might be bad but I was losing vacuum at the supply side. However, I had consistent vacuum from the pump that never faltered. It was almost like a solenoid valve was cutting on and off which is what made me think N75 might be the issue.
I noticed that when pinching the hose going to the vacuum reservoir on the valve cover the vacuum would go to normal. Investigating further, it turned out that the rectangle door in the valve cover that covers the reservoir was leaking around the edge. I didn't even know it was a cover until this (see picture below). Most diagrams show the vacuum reservoir as a round plastic ball. My understanding is that at some point, VW replaced the ball with this little compartment inside the valve cover. For some reason, they put this little cover on the top and it apparently comes unsealed. I read another contributor on the forum suggesting the same thing.
I took a large screwdriver and gently snapped the cover off all the way around it (you could break this thing if not careful). I then mixed some epoxy and glued the cover around the entire parameter.This solved my Under boost /Limp issues. Just wanted to share in case this helps someone in the future.
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