kayak01
Active member
I took my 04 jetta wagon to a local mechanic for the check engine light. Code 16683 - turbo underboost. What does that mean? How do I fix it? and how do I keep it from happening again?
Turbo Underboost
- Thread starter kayak01
- Start date
alphaseinor
TDI Innovator, Gone but Not Forgotten
- Joined
- Jul 30, 2006
- Location
- Denton, TX
- TDI
- '03 Jetta TDI 780,000 miles (totaled out), 01 Audi TT 225 Quattro 230,000 Miles (runs great!), 00 Cabreetle Beetle dash, ALH & MK4 harness Swap
Underboost is where the computer requests a certain amount of boost, and the turbo delivers an amount less than requested.
The '04+ have much better vacuum lines, so that's "probably" not it... my bet is on the VNT actuator, loose vacuum line, or an N75 valve.
Most PD engines won't clog the intake like the VE engines, but who knows... might as well pull the EGR valve and take a look.
The '04+ have much better vacuum lines, so that's "probably" not it... my bet is on the VNT actuator, loose vacuum line, or an N75 valve.
Most PD engines won't clog the intake like the VE engines, but who knows... might as well pull the EGR valve and take a look.
gforce1108
Top Post Dawg
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- Aug 2, 2006
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- Newburgh, NY
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- 04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
The vacuum lines might be better, but they are certainly not great... On my '04, the line from the N75 to the turbo wore through where the dealer routed it wrong (EGR recall). Check that line and go through your intercooler tubes. The one at the top (EGR connection) pops out very easily. There's a nice repair kit selling on the forums. I also added thicker orings in every connection from the turbo to the engine to prevent boost leaks.
kayak01
Active member
Thanks, I'll try all of that as soon as it stops snowing. Is it a bad idea to keep driving until she's fixed?
HopefulFred
Veteran Member
It's probobly not too bad, but that means the turbo is trying to produce as much boost as it can, pretty much all the time. It's lot of work for it.
gforce1108
Top Post Dawg
- Joined
- Aug 2, 2006
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- Newburgh, NY
- TDI
- 04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
If I understood my VAG-COM logs correctly, the N75 was trying to make boost all the time, but the turbo was not, since the actuator was not moving correctly. Mine slowly got worse as the line rubbed through more, eventually going into limp mode and throwing a code.
If there was a boost leak it would be much harder on the turbo.
If there was a boost leak it would be much harder on the turbo.
d2305
Veteran Member
I have the same problem, but it's too hot out to work. I wish I were in Jackson Hole.
TornadoRed
Top Post Dawg
- Joined
- Aug 3, 2003
- Location
- West Des Moines (formerly St Paul)
- TDI
- 2003 Jetta TDI wagon, silver; 2003 Jetta TDI wagon, indigo blue; 2003 Golf GL 5-spd, red (PARTED); 2003 Golf GLS 5-spd, indigo blue (SOLD); 2003 Jetta TDI wagon, Candy White (SOLD)
Too bad we never found out if kayak01 solved his problem.
d2305
Veteran Member
Driving up a 8000 ft. mountain will suck up the fuel. He's lucky to get 38mpg. I looked at all my vacuum lines and hoses, and they all look good. Guess I need to find a guru.
Last edited:
ofhs93
Veteran Member
if all of the hoses and lines checked out ok try checking out your VNT actuator....the diaphrams in them have been known to fail (mine is borderline right now...does not hold perfect vacuum)....if it can't hold vacuum then it wont move the vanes in the turbo to create boost.