[crod_E90]

So, I had the family mech run his OBD scanner since I dont own one and it picked up 13 trouble codes. Any help as to what they are exactly and what I can do to fix the issue is greatly appreciated. I love my E90 and I’m willing to dump money into her. I know my O2 sensors were cut as an attempt to steal my catalytic converters but it hasn’t affected my drivability at all. But, my N51 did start to overheat randomly just the other day.

[lowrydr310]

Originally Posted by crod_E90

I know my O2 sensors were cut as an attempt to steal my catalytic converters but it hasn’t affected my drivability at all.

Repair that first, clear the codes, then see what comes back.

Search the forum here for K+DCAN cable and the BMW tools. That cable along with the software installed on a laptop will help you much more than a standard reader with generic OBD2 codes.

[gbalthrop]

Originally Posted by crod_E90

... I had the family mech run his OBD scanner since I dont own one and it picked up 13 trouble codes... my O2 sensors were cut as an attempt to steal my catalytic converters but it hasn’t affected my drivability at all... my N51 did start to overheat randomly just the other day...

I would suggest having ALL codes in ALL Modules read by a capable Scan Tool or Diagnostic Software (INPA/ISTA). The P-code reader used to read Engine/ DME fault codes cannot see Hex-codes such as 2E81 - 2E85 which relate to Coolant Pump function.

You have had "Misfire" fault on EVERY cylinder. That is what the P0301 - P0306 fault codes mean. P0301 is "misfire, Cylinder #1", P0302 is "misfire, Cylinder #2", etc. If the engine is running smooth MOST of the time, then those are RANDOM "misfires" and NOT Constant. Freeze Frame Data, which is a "Snapshot" of system conditions, including Temp, RPM & Odometer reading, at moment Fault Code was saved, would offer clues related to the "misfire".

A "Misfire" is anything that causes momentary slowing of crankshaft rotation speed, due to LESS power on Power Stroke of certain cylinder vs. that of cylinders preceding & following in the firing order. So "Misfire" can be caused by Injector or fueling issues as well as Spark Plug, Coil or wiring issues. Don't just "Throw Part$$". Get FF Data for each Fault code & Post here.

You may have connectors reversed for Pre-Cat O2 Sensors. P0171 means Bank #1 (cylinders 1,2,3) are Too LEAN, while Bank #2 (cylinders 4,5,6) are Too RICH. Watching STFT (Short Term Fuel Trims) as engine warms from cold start would help diagnose that issue. Swap connectors (don't remove sensors) and see if those codes go away. Reading fuel trims as live data with engine running is better diagnosis.

P0492 indicates "Insufficient Flow" from Air Injection Pump (located next to Coolant Reservoir) to Bank #2, probably due to issue with supply hose or check valve.

P0056 indicates O2 Sensor HEATER circuit on POST-Cat O2 Sensor is NOT being activated, probably due to wiring fault. You do NOT show any O2 Sensor HEATER circuit fault for any of the other three O2 Sensors. You do NOT show any fault for either Post Cat O2 Sensor SIGNAL.

P0073 indicates an issue (probably wiring damage or open circuit) in Ambient Temp Sensor Signal. That Sensor is located in center of front spoiler area. Any damage there? Are you getting any Ambient Temp reading on Instrument Cluster? Like -40? That should NOT affect engine performance or any other fault code.

If you have either a Windows Laptop, or an Android device, I would recommend inquiring about reasonably-priced (< $100) Diagnostic Software Solutions. You can get a Scan Tool that can read P-Codes, FF Data, & Live Data such as Fuel Trims (in DME only) for $35 from Amazon. Fault codes alone, WITHOUT FF Data & Live Data (Parameters), don't provide much diagnosis.
George