Can a Brake booster leaking vacuum...

[ranger7ltr]

Can a leaking brake booster cause a lean code? My truck started throwing P0171 and P0174 codes at me recently and I know the booster leaks as I have no brake pressure 10 secs after I kill the engine...My vacuum gauge though shows a good solid 20-22 in./hg. vacuum so it can't be a big leak...I guess...

The intake gaskets should not be leaking as they were installed about a year ago and the bolts are tight...

I have been tracking down vacuum leaks and it would seem that the more leaks I fix the more the lean codes show up...I replaced vacuum lines to the purge valve, the pcv valve, and i am checking the rear canister lines this weekend...

And the truck runs fine so if it is a vacuum leak it is not affecting driveability...

 

[jlsparky7]

Definitely can and usually does.

 

[jremington59]

It could be a dirty MAF sensor but if you know you have a vac leak it very well may be that.

 

[budwich]

there are ways to test your booster based on response of the pedal to force at idle and revved... search should help. I would agree with previous post that you might be "barking up the wrong tree".

 

[Radiojunkie]

My brake booster also leaks and I now use it in "manual mode". Yes, it will be a big vacuum leak to your engine. I plugged off the intake side for now until I can get a new booster. About 60 bucks at autozone.