325xi O2, limp, multiple codes

[Zukrol]

So hard to figure out where to even begin.
2005 325xi
Recent projects - Valve cover gasket, spark plugs, spark plug boots and the thermostat + housing.

Was getting an O2 sensor code for about 3 weeks, bank 2 sensor 1 i believe. Along with that code was a P0174. Bank 2, system too lean.
Occasionally getting a Misfire detected with low fuel, I've planned on doing injectors for a while. Pump is less than 1 year old.

Now we come to last night. 8:30PM, 45 miles from home I pull up to a gas station, run inside while leaving car running. Wife was inside the car.
When I got back in, put it in reverse everything seemed normal. As soon as I put it in drive i realized i had minimal power.



The car when into limp mode, along with the - ABS, Yellow BRAKE light and the traction control light. Brake pad wear sensor has been on, forgot to replace sensor.


At this point I cleared the codes with my Bluetooth scanner to see what would come back. It became a game. Some codes came back, others vanished and didn't return.
I drove the car home, as limp mode felt like it was around 4th gear.
Scanned it today with a snapon solus scanner and learned a bit more.

Codes that came back were
p0031 - HO2S heater control circuit low Bank 1 Sensor 1
p0037 - HO2S heater control circuit low Bank 1 Sensor 2
p0051 - HO2S heater control circuit low Bank 2 Sensor 1
p0057 - HO2S heater control circuit low Bank 2 Sensor 2
p0600 - Serial communication link

And the new issue -
Electronic Transmission Control (EGS) Signal.

At a loss, not sure if I should change all of the O2 sensors or worry about the tranny code,

Before clearing codes

car1.jpg

After clearing codes and driving home for lunch

car2.jpg

[Zukrol]

Small update about the O2 sensors. Grabbed a couple screenshots of the voltages while driving a few moments ago. Not sure if it helps any, I was just curious.
Screenshot_20180918-221139_Torque.jpgScreenshot_20180918-221207_Torque.jpg

[dhurley34]

What is your fuel pressure? Vacuum leaks? Intake boots? Lean conditions can cause all.of that including limp mode.

Don't worry about the upstream O2 voltages. They are supposed to switch from 0.1 to 0.9v back and forth really fast.

[Zukrol]

Found 1 very small tear just behind the MAF earlier. Ordering a new boot tomorrow morning. Also found a very dry hose that is starting to crack, i believe its the secondary air valve, not sure how important it is though. Will monitor fuel pressure in the morning.
Planning on injectors within a week, and honestly have no idea when the fuel filter was last changed. I bought the car at 92k miles, currently 141k and I haven't done it. Might as well add the fuel filter when i do injectors.

I should note that while the computer detected misfires, I have felt nothing.

[randy72877]

Fuse f4 in the dme box powers all o2 sensor heaters and also the trans control module. It's probably blown. It's a 30A fuse in the fuse holder shown in the picture.

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[Zukrol]

Fuse was blown. Replaced and it popped in 2 seconds.

[randy72877]

You have a short circuit somewhere. You recently replaced the vcg. Check for o2 sensor wires pinched under the vc, especially in the back of the engine.

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[randy72877]

Here is the wiring diagram.

https://www.newtis.info/tisv2/a/en/e...xi-lim/jou3I3I

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[por911]

I'm with the others, replace the fuel filter/regulator. I'd also take care of the vac leaks before addressing O2 sensors. I just replace the intake gaskets, injector o-rings, all crankcase vent hoses, vac hoses, and ccv on our 330xi which really helped smooth things out.
DSC_0001.jpg
I'd previously replaced the fuel filter/regulator and pump assembly. We were having a couple o2 sensor codes, but they went away(knocks on wood). Our car only has 67k on it. Hope this helps.
Regards

[randy72877]

I'm with the others, replace the fuel filter/regulator. I'd also take care of the vac leaks before addressing O2 sensors. I just replace the intake gaskets, injector o-rings, all crankcase vent hoses, vac hoses, and ccv on our 330xi which really helped smooth things out.
DSC_0001.jpg
I'd previously replaced the fuel filter/regulator and pump assembly. We were having a couple o2 sensor codes, but they went away(knocks on wood). Our car only has 67k on it. Hope this helps.
Regards

The car is blowing the fuse for the o2 sensor heaters/trans control module. Transmission in limp mode. This needs to be fixed FIRST. Then look for vacuum leaks ect for lean/misfiring issue

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[Zukrol]

Next step is the intake boot, fuel injectors and filter. If i started ordering that much stuff now, fiance would murder me. Wedding is next Friday. After that, ill start replacing more

Started looking at the o2 sensor wiring after work. Noticed immediately the wiring for bank 2 sensor 1 was sitting on the exhaust manifold. Must have forgot to clip it back up.
Repaired the melted wires and it runs great again. Not a single code.
20180919_171546.jpg

[MarcoZandrini]

After the wedding your life will drastically change!!! Trust me!