Engine code 171 - 1999 BMW 318 ti

Well code 171 is telling you the fuel mixture is too lean for bank one and code 174 is too lean bank two.
So the most common cause is low fuel pressure.

According to the page I found at Toyota, it's a "Random cylinder mis-fire" - meaning it is not happening consistently. Here is the site for the code 300: http://engine-codes.com/p0300_toyota.html.

Also according to the same site, on this different link, is your code for the 171 which states that it is a " fuel mixture system being lean on bank one" of your engine. The site goes on in substantial detail in both cases to tell you what the cause could be and how to fix them. Best of luck with it, hope you can do it yourself. Here is the other link: http://engine-codes.com/p0171_toyota.html

Well code 300 is a random miss, 301 is for cylinder 1 and 306 is for cylinder 6. Code 171 is saying the fuel mixture on bank one is too lean. And that could cause the other codes.
Have you checked fuel pressure and the filter ?

Lean report from right side bank #1 oxygen sensor

Replace both sides upstream sensors if over 100,000 miles

They slow down & set a mil lamp

Leave the rear monitors

this should take some of the guess work out


http://www.aa1car.com/library/ford_lean_codes.htm

did they ever reflash the ecm with the new codes for the motor

http://www.automotiveforums.com/t473813.html

PO 171 is a system to lean code. This link will explain why this is and how to fix it,

switch, we run off snitches. 171 174 banks 1 & 2 Lean. Most likely cause are Upper Intake Manifold Gaskets, failed seals. It's not 1990 on. It's 1996 and on OBD2.

first check out for o2 sensor if its faulty this can show up.but if its proper.Evaporative emission control system leak very small 171 System too lean (bank 1) 174 System too lean (bank 2) 

I looked up code 171 and found 'system lean bank one' Sounds like a fuel injection sensor. countrycurt0