It could be any of these

A faulty fuel pressure regulator
A weak fuel pump
A clogged fuel filter
A faulty powertrain control module
A vacuum leak
Faulty injector(s)
Faulty oxygen sensor(s)
A faulty mass air flow sensor

What exact car do you have? I cannot help with your problem, I'm just curious as I love VW

Just an update on this, found my PCV valve was sucking in air. Once I get paid Thursday I'm buying a PCV revamp that will cut off the catch can and turn the PCV system to a full vacuum system. Better performance, throaty idle, all things I can support.

For future reference if anyone has this issue, spray around the maf sensor with brake cleaner and work your way around the motor. You'll know you found your leak when your car idle runs different.

For VW owners, if you have this code try removing your oil cap while running, if your idle goes bad check your PCV valve or your intake gasket. Both could lead to that issue.

KyloCrux wrote Just an update on this, found my PCV valve was sucking in air. Once I get paid Thursday I'm buying a PCV revamp that will cut off the catch can and turn the PCV system to a full vacuum system. Better performance, throaty idle, all things I can support.

For future reference if anyone has this issue, spray around the maf sensor with brake cleaner and work your way around the motor. You'll know you found your leak when your car idle runs different.

For VW owners, if you have this code try removing your oil cap while running, if your idle goes bad check your PCV valve or your intake gasket. Both could lead to that issue.

Do you know how long you were running with the check engine light?

I had the same PCV valve issue on my A3 2.0T, but I wasn't getting lean codes at first. I wasn't getting a very rough idle, only heard a whistle at higher rpm so I thought it was a vacuum leak at first. Did the dip stick test three months ago, only to find out a new problem last month.


About one to two months later I experienced the worst cold start, car was misfiring so bad I had it towed to a shop. Car only recorded misfires, and random misfires on all cylinder but no lean. Car started to run better, so we thought it was related to some possible bad gas. Checked the oil, and saw it was a little low as well. Threw it up on the lift, and that's when we found oil near the rear main seal. Let it sit for a few days, and there was a small puddle under the car. We topped it off with oil, and now we are starting to see lean codes now.

Just thought I would share my recent experience with my bad PCV valve.

Forest wrote

KyloCrux wrote Just an update on this, found my PCV valve was sucking in air. Once I get paid Thursday I'm buying a PCV revamp that will cut off the catch can and turn the PCV system to a full vacuum system. Better performance, throaty idle, all things I can support.

For future reference if anyone has this issue, spray around the maf sensor with brake cleaner and work your way around the motor. You'll know you found your leak when your car idle runs different.

For VW owners, if you have this code try removing your oil cap while running, if your idle goes bad check your PCV valve or your intake gasket. Both could lead to that issue.

Do you know how long you were running with the check engine light?

I had the same PCV valve issue on my A3 2.0T, but I wasn't getting lean codes at first. I wasn't getting a very rough idle, only heard a whistle at higher rpm so I thought it was a vacuum leak at first. Did the dip stick test three months ago, only to find out a new problem last month.


About one to two months later I experienced the worst cold start, car was misfiring so bad I had it towed to a shop. Car only recorded misfires, and random misfires on all cylinder but no lean. Car started to run better, so we thought it was related to some possible bad gas. Checked the oil, and saw it was a little low as well. Threw it up on the lift, and that's when we found oil near the rear main seal. Let it sit for a few days, and there was a small puddle under the car. We topped it off with oil, and now we are starting to see lean codes now.

Just thought I would share my recent experience with my bad PCV valve.

The code kept coming back everytime I would erase it. Ran with it for about two months before finally diagnosing it. A dead giveaway for me was the oil oozing out of the cap. Putting the PCV revamp on it Friday. So excited for my car to not idle like crap and start on a dime again.