Trans Program Failure and O2 OBD codes - ideas on the cause
 

My 2003 X5 4.4 Sport (M62) which I have owned since Feb (bought it with only 44k miles) now with only 54k miles, gave me a Transmission Program Failure a few weeks ago (shown on dash display) and went into a failure mode, limited shifting. Never any problems before. I shut it down and restarted and the problem went away and the transmission shifted fine. A few days later, same thing. I shut it down and restarted and the problem was gone. The car has been running great with no other problem.

That was about two weeks ago. Now apparently a new problem, or maybe something related. This weekend, the SES came on with P0030 (HO2S Heater Control Circuit, Bank 1, Sensor 1) and P0031 (control Circuit Low Bank 1), P0037 (Control Circuit Low, Bank 2). I checked the wiring, visual only, and everything looked in order. After reading how sensitive the Bosch DME ME 7.2 system is to voltage, and needed to run with about 12.6V, I checked and found the battery was only putting out 11.82V. Not knowing how old the battery was, I replaced the battery hoping low voltage was the problem in both the strange transmission shift problem that disappeared, and now the range of OBD codes all related to the heating circuits for the 4 oxygen sensors.

No such luck. I erased the codes, and with the new fresh battery, the SES is back on and I just got P0030, P0050, P0037, P0057 and P2271 and P2273. All related to the O2 sensors. It doesnt make sense to me that its all the sensors are bad, so it must be something common to all.

I did check the ECM wiring diagrams and Pin assignments, and its curious that both the oxygen sensor circuits and the automatic transmission control module (AGS) are all related to Connector 2 (X60002) on the ECM. I have not tried to disconnect and reconnect just yet. The ECM in the engine compartment looks high and dry and normal so I have not attempted to open and check it out further.

Any ideas on where to look next before I break down and try a dealer (last resort...) I usually like to fix this stuff but this one has me guessing. So posted to this forum for some ideas.

Alternator?

Well, thats a good start.

When you say it was 11.8 volts, was that with the engine running? If so, ignore the rest and get an alternator.

The o2 sensor codes, did they all come back with a heater code? Sorry, just read, yes they did.
Those are going to have a fused power source somewhere, its time to get back to the diagrams/fuse assignments and figure out where the o2 sensor heater fuse is (or what it shares a fuse with)

You might need to get out of the OBD codes and into real BMW codes to get more transmission info.

With the new battery, just checked and now 12.15v across the new battery, with all cables attached, ignition OFF, just like Bentley Service Manual specifies. Better than the previous 11.8V with the old battery, measured the same way, but below the 12.6V or slightly more they indicate I should expect for a fully charged battery, so I will run it a bit and see if the charge comes up. Not sure if this is even the right path to pursue, but the voltage is below spec at this point.

See link in my sig. Read it. Unlock OBC, and do the voltage test while idle. Lets see if you stay above 13.5 while the car is on. Oh turn on lights, music, stuff like that as well. Not AC. AC actually bumps idle.

An update. I was going down the wrong path on thinking this was all a low voltage problem.

I went over the wiring diagrams and found that there is a 30A fuse located in what they call the Engine Electronics Fuse carrier, which is located under the ECM cover, which is located just under the windshield at the right rear of the engine compartment (lots of fuses on this car, behind the glove box door, in the cargo compartment in the rear, and now a small block of five 30Am fuses in the ECM carrier. Fuse #3 is for the oxygen sensor heating circuit.

After some disassembly to get to it, I found that #3 fuse was blown. I replaced and it blew again, so obviously I have a short. Could be one of the 4 O2 sensors or in the wiring harness from the ECM to the sensors, so I am now trying to chase that down. Once that fuse blew, the entire O2 sensor heating circuit was out, both left and right exhaust banks, so I got the P0030 and P0050 codes for the circuit problem, and then all the other codes on low voltage (no voltage in this case).

Wish me luck as I hope to chase out the short location and get this solved. Hopefully, its one of the oxygen sensors shorted and brought the circuit down. Will know the weekend if I can get to work on it.

Good start.

An easy test to start with would be to unplug all 4 oxygen sensors and pop in another fuse.
I haven't seen it but is is possible a heater has shorted. If it still does it, your stuck with hunting down anything else on that fuse and tracing the harness around.

I think its more likely one of the harnesses is touching the exhaust and melted or something else and chaffed though.

Good luck on the hunt, shorts can be a pain to chase down.
Keep us updated on the progress.

Agreed. Great start. Keep us updated.

Ok, found it. And it might be a problem on other X5's.

The cable to driver side, post catalytic converter O2 sensor was rubbing on the transmission output yoke. It shorted against the driveshaft. Big surprise that a section of cable was loose and could touch the driveshaft since all the other O2 sensor cables are routed and clipped against the transmission. This one spot would be logical to tie down better to avoid the driveshaft, but it was looped and touched over time wearing through. I fixed it, replace the fuse and everything is fine.

I will include a photo of my fix when I have a chance since i added a small plastic loop held by a self tapping screw in a place on the rear of the transmission that looks like it was meant for this, to keep the cable away from the driveshaft so this doesnt happen again.

Problem solved. I would check other 2003 X5's to see that the cable clears the driveshaft. A pain to find but glad I found it and could fix it.

Hi, well traced, that sounds very similar to what's happening to mine. trans prog failsafe error when you turn the key to position 2 before engine starts,code referred to valve block ass'y but indy has told me valve block and solenoids all check out. I will have him check this.

thanks