P0411 code Question! Can u clean O2 sensors or do you have to replace have 2003 BMW 325i trying to nail down the problem for code

it is normally the HO2S ( heated oxygen sensor) in the exhaust manifold before the cat converters
That unit reports the exhaust gas composition to the ECM which adjusts the mixture according to the MAF/VAF sensor readings
Add to all of those the ambient temp sensor and the BARO sensor and you have the system that adjusts the air/fuel mixture
how to fix
have the fault codes read and replace the faulty sensors

this code does not exist in my BMW code list ,so contact the manufacturers of you cheap hand held code reader for a explanation
P1176 O2 Sensor Slow Response Bank 1 is the nearest i can find

code po444 is referencing a purge control problem. this could be a bad connection or a problem with the purge solenoid for the evaporative system(EVAP). this is controlled by the PCM to allow fuel vapours to be drawn into the engine and burnt from the gas tank under certain conditions. the p0174 is a lean running condition on bank 2 and p0171 is a lean running condition on bank 1. the lean running conditions could be O2 sensors, lean condition caused by bad fuel pressure, dirty injectors, bad MAF sensor, vacuum leak.

P0140 BMW P0140 BMW - O2 Sensor Circuit Low Voltage Bank 1 Sensor 2



Possible causes - Faulty Rear Heated Oxygen Sensor Bank 1
- Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem
http://engine-codes.com/p0140_bmw.html

dirty air filter - bad o2 sensor etc etc .

Hi Adam, I believe the most cost effective action for you is to get the management system designed for your engine. When doing so it may well be required that you also purchase the wiring harness that goes with the replacement unit. Regards John

That code reads "fault with O2 sensor before catalytic converter". Replace the O2 sensor and clear the code and your good to go.

many reasons for this. A bad relay can do it, or a wheel speed sensor can to. Also the relay may be at fault. You can have the codes checked for free at any Auto Zone and they will tell you what part is bad

You have to be able to monitor them while the veh is running,need to take it to bmw dealer because they dont release the software for aftermarket diognostic machines.

This is an O2 code, I have been told by a BMW tech that poor quality fuel can cause this as well as a dirty fuel filter which causes a slight loss of pressure and a stumble, I would do this, change the fuel filter, clean the MAF sensor for good measure and switch brands of fuel, otherwise a trip to the dealer may be in your future, average cost to repair this is about $250.00