SES light on: P0171 P0174
 

my X5 just has 42k miles. I had the SES light on today, so I went to AutoZone to read and clear that. Then I have a code P0171 and P0174
I guess I have a bad O2 sensor(that early at 42k miles??) or I did fill some bad gas (just fill 93octane at Hess)

It states at the printout that
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OEM Number P0171

Definition
Fuel trim bank one condition

Explanation
The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine.
The computer has recognized a rich or lean condition on one engine bank only.

Probable Causes
1-If bank one and two codes set together suspect fuel pressure or MAF sensor
2-Oxygen sensor defective
3-Ignition misfire-repair
4-Fuel injector problem

Troubleshooting P0171
The PCM has determined that during testing, the fuel system for bank 1 was too lean. (Bank 1 identifies the location of cylinder #1. While bank 2 identifies the cylinders on the opposite bank)

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Oem Number P0174

Definition
Fuel trim bank two condition

Explanation
The ECM has detected a rich or lean air/fuel ration condition on engine bank two

Probable Causes
1-If bank on and two are set together suspect a fuel condition or MAF sensor fault
2-Failed H02s21
3-Ignition misfire condition
4-Fuel ingector problem
5-Engine mechanical condition

Troubleshooting P0174
The PCM has determined that during testing, the fuel system for bank 2 was too lean. (bank 1 identifies the location of cylinder #1, While bank 2 indentifies the cylinders on the opposite bank)
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Check the air intake hose that connects to the throttle body for leaks.

Also check your gas cap, I just replaced mine because I was getting those codes all the time and it hasn't happened since.

thanks so much for the input!!
I just found out there is a crack on the last section of the intake hose. (BMW use cheap rubber hose)
So I call my local BMW, and fortunetly they have that in stock now and cost only $15.

Royal pain in the butt to do but will cure the problem cheaply!

Clean the MAF when you are in there, that rip is very common for 3.0 X5's and can introduce dirt to the intake.