BimmerFest BMW Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Keep getting an error code saying my bank 1 and 2 are running lean and just wanted to see if anyone else has had this problem before I shell out some cash to get it fixed. If you’ve had these codes before (p0171/ P0174) how did you fix it and what caused it?


Sent from my iPhone using Bimmerfest mobile app
 

·
BeeemerBro
5,4,6 BMW X3 All...196K +
Joined
·
3,518 Posts
Keep getting an error code saying my bank 1 and 2 are running lean and just wanted to see if anyone else has had this problem before I shell out some cash to get it fixed. If you’ve had these codes before (p0171/ P0174) how did you fix it and what caused it?


Sent from my iPhone using Bimmerfest mobile app
See what these guys say...
https://www.bimmerfest.com/forums/showthread.php?t=1309467

https://www.bimmerfest.com/forums/showthread.php?t=1305227

https://www.bimmerfest.com/forums/showthread.php?t=1308139
Sent from my SM-J727T using Bimmerfest mobile app
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3 (Edited)
Bank 1 & 2 running too lean

Mostly posting to see if It would be safe to drive it back to college this weekend (only 120 miles) while those codes are showing up. I’ve read that it can destroy your engine if you run it lean for too long.
 

·
Anti-Hack
Joined
·
4,920 Posts
Bank 1 & 2 running too lean

You’ve likely a vacuum leak, most likely in the rubber air intake. IIRC the M54s have a slightly different intake plumbing with a small bellows that is notorious for cracking. If you find it, you can temporarily fix with duct take to get you going. You definitely don’t want to drive long or far, especially in winter, as drawing in the unfiltered air will destroy your compression. Running too lean for too long can also melt the pistons... had an Olds 307 years ago that was running lean and heat melted the electrode on the #2 plug.


Sent from my iPhone using Bimmerfest
 

·
Registered
Joined
·
485 Posts
As long as no CEL, you're fine but should get it fixed...you'll have engine hiccups along the way...drove mine lean from Albany to MD
 

·
Registered
Joined
·
8 Posts
Discussion Starter #7
Checked again today and got a cylinder misfire code for 4 and 6. Luckily I had bought 2 extra Bosch ignition coils when I replaced them awhile back. Popped those bad boys in and everything is running smooth. No more running lean code and rough idle is gone! Thanks to everyone who posted!


Sent from my iPhone using Bimmerfest
 

·
Registered
Joined
·
485 Posts
Vacuum leak if left long time...like you really have to not care, then yes....o2 sensors usually cause a rich condition if defective, but air:fuel sensors can cause the catalyst below efficiency code as well
 

·
Anti-Hack
Joined
·
4,920 Posts
Bank 1 & 2 running too lean

Maybe maybe not, but why take chances? Yes those are extreme case but do illustrate the damage that can occur. Noting the 3 lb lump hammer for scale, you can tell those pistons came out of an engine that doesn’t use a computer, a 30 liter or so Cummins V12 to be exact.


Sent from my iPhone using Bimmerfest
 

·
Registered
Joined
·
8 Posts
Discussion Starter #13
Made the drive back with no issues, gonna check and make sure there is no vacuum leak just to be safe


Sent from my iPhone using Bimmerfest
 
1 - 13 of 13 Posts
Top