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JayPutelis, Shop Foreman/ BMW Master Tech
Category: BMW
Satisfied Customers: 866
Experience:  12 yrs Experience; ASE Master Technician; ASE L1 Certified
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2010 335xi ,,check engine light is on code po171, comes back

Customer Question

2010 335xi ,,check engine light is on code po171, comes back on after 10 miles,,,has slight engine miss when first started for a minute,already replaced 4,5,6 injectors and had coded
Submitted: 1 year ago.
Category: BMW
Customer: replied 1 year ago.
Changed injectors for misfire codes and those codes have not returned
Expert:  JayPutelis replied 1 year ago.

Hi there, do you have a BMW scan tool that can look at diagnosis requests of sensor values?


Customer: replied 1 year ago.
Expert:  JayPutelis replied 1 year ago.

What are the adaptation values for bank 1 and 2, additive and multiplicative.

Customer: replied 1 year ago.
I'll have to check in am r u avail tomorrow
Expert:  JayPutelis replied 1 year ago.

Yes, just respond back to this post.

Customer: replied 1 year ago.
my tech told me he smoke tested and found a small crack in valvecover could this be causing lean code
Expert:  JayPutelis replied 1 year ago.

Yes. 100%. A cracked valve cover causes an unmetered air leak into the crankcase system. Hence, throwing the lean code. Unfortunately the valve cover will need to be replaced which is costly.

Please don't forget to leave a positive rating, as this is the only way I receive credit for my work and time.

Thanks, JP

Customer: replied 1 year ago.
jay still have lean bank 1 code ,I replaced cracked valve cover,otherwise seems to run perfect,im sorry I didn't rate yet ,trying to get this fixed
Customer: replied 1 year ago.
cant check the valuations
Expert:  JayPutelis replied 1 year ago.

Lean codes are caused by two things, too much air (which could be an intake leak such as a cracked valve cover), or not enough fuel (such as clogged injectors). The way to test for injectors is to compare adaptation and smooth running values between cylinders. You will need to find a shop with a quality scan tool to do this if your tech doesn't possess one.