2001 bmw 330xi codes help

I have a 2001 330xi it is reading codes P0174 P0171 P1620 P1083 P1085 Ive read what the codes mean but dont understand how to go about fixing the problem your info would be greatly apreciated

By my experience...

The car computer is telling you what is failing. Some sensors "fails" because of a bad reading from others. Some sensors are fine but the connections are bad (happen to me), others the sensor itself is done for.

The car computer has set parameters, if one or 2 are off, the others seems to be "wrong" since the computer sees the absurd data coming to it. Like for example, the air coming in the intake is volcano hot but the density is too thick for that temp and the EGR valve opens and the engine idle drops and start misfiring. So the computer says, Sensor X, Y and Z are wrong. In reality is one making all fail due to bogus parameters.

If you go to the local Auto Zone, you could test it by replacing one sensor at the time. On my case, they allowed me to return the sensors. I bought 2 Sensors of the same kind and turned out to be a bad connector. I got a refund !

Get a scan tool, is a must have. Buy the one that you can read the data on your car while is running, like RPMs, Manifold Press, etc...

I used one and has a cable long enough to take it by the engine and wiggle the cables. You will see sensors that read, for example 240C or -39C, those are unreal numbers. That mean the Sensor has no electrical input (too cold) or has a broken wire or is a short on the wire or the sensor if it reads 240C or so. That is on the Temp sensors. You can disconnect them and see if it changes if it does is the sensor if it does not is a bad wire.

What I will tackle first are the one with extreme readings. Like way too cold/hot when is not, way too high or low RPMs, same with pressures, etc. That is a good indication of a bad sensor or a bad connection.

That is why is handy to have a scanner that can be taken by the engine, so you can mess with the sensors and see if some changes.

Replace that sensor/fix connection and clear the computer, see what new codes comes out. Perhaps all of them are gone or just one might come out.

I hope this helps.

I would get it checked by a bmw dealer or a tech familiar with those cars! I'd stay away from Parts stores and kids with code readers if I were you!