My bmw is over heating I don't no what is a problem

if you don`t want to weld it then you can try exhaust tape that you wrap around the hole and get the exhaust hot and it will harden. don`t know why you don`t want to weld it. or you can replace the exhaust component that is bad.

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

Sorry mate take it to BMW if you don`t have the ETM DON`T make it harder for yourself these cars are not Fords and will cost you more if you don`t have the right tools

This can only be done with a B.M.W service tool,try a motor factors for one they don`t cost much and do all B.M.W`s(charge your mates for a lights out soon make ur money back!!!!!!!)

Your security code is in the BMW owners manual.
If you do not have the manual then you need to go to the BMW service centre to get this code.

I presume the fan does not run on vent or heat either? The most likely cause of no moving air is a failed resistor that controls the fan speed. This was a common problem on this model, and on the previous generation of 3-series BMW..
The original resistor was made by Behr for BMW, so you might be tempted to replace it with an alternate brand part, since this one failed, but Behr claims that they have improved the design of this part since the car was originally built. The resistor should cost you about $65 on line or $120 at the dealer. I have not installed one on an e46 so I don't know exactly where it is or how much work it takes to get to it, but fan resistors generally are not too bad. Should cost around $100 to install if you pay someone else to do it.

Assuming that you have checked the fuse for the fan, the most common problem is the resistor that controls the fan speed. That has been problematic, and BMW has tried several designs for this resistor. Current design part costs about $55 on line. I don't know where it is mounted on this model, but it will be under the dash near the center somewhere.

The 5-61 is the 2007 525XI diagramThe 6-46 is the 2003 M5 diagram - I don't have a listing for the 2003 525I

the problem could also be your radiator cap and you need to make sure that you don,t have an air bubble in the system you also have to have the right amount of anti freeze in it but try the cap first seems so simple but it is a good possibility. hope this helps

sounds like engine management chip fault,may be worth getting checked at dealers as will show on diagnostic machines hope this helps andy