E46 330ci Engine light with E3/E4 fuel trim fault

[KittyG 8]

Hello guys! My E46 got the engine light on and after one month the light pop out again. Scan both time for the same code which is E4 fuel trim bank 2, permissible range exceed and E3 fuel trim bank 1, permissible range exceed.

I’ve check through the online for long time, all recommended likely the issue is bad O2 sensor, vacuum leak or MAF bad.

Any one got this fault before on E46? Any recommend place for a smoke test (don’t want to pay for diagnostic again please…)

Please help thanks.

[BM WORLD 1283]

start with vac leaks , many places they can leak from , many old rubber and plastic hoses that can crack etc 

[NZ00Z3 187]

Read this thread.  It will get you started:  https://www.e46fanatics.com/threads/fuel-trims-lean-codes-misfires-and-how-to-diagnose-p0101-p0174-and-more.1284608/

Getting a cheap OBD2 scanner so you can do your own engine tests does not cost a lot.  Get OBD Fusion on your smart device and buying the cheap OBD2 adapter (WIFI for Apple or Bluetooth for android) gets you set up.  See this thread: https://www.e46fanatics.com/threads/obd-fusion.1240733/#post-18380161