[mikeypx82]

I need help troubleshooting my automatic air recirculated control sensor in my '05 330i. I'm getting this error:

32 AUC heating
Error Frequency: 10
Short circuit to ground
Error present
Error code: 20 42 0A 51 34 A8 08 11 03 6F

When I clear the code, it comes back immediately. When I unplug the AUC sensor I get the error message above plus this one:

30 AUC Sensor
Error Frequency: 10
Open circuit
Error present
Error code: 1E 44 0A 84 37 A8 08 20 03 6F

I bought a used AUC sensor from eBay and I'm getting the same results. I inspected the connector that plugs into the AUC sensor and it looks OK. I took a multimeter and tested each of the pins on the connector. These were my results:

While touching one probe to ground on the chassis, pins 1, 2, and 4 are indicating a connection to ground. Pin 3 is showing 1800 ohms of resistance to ground. According to WDS only pin 1 should be connected to ground. I've attached a picture of the diagram. So, I believe my problem is that pins 2 and 4 are grounded when they shouldn't be. The wires leading to the connector look fine. Not sure where to go from here.

Can someone test out the pins on their connector and verify which pins are supposed to be grounded? Any idea where the wires might be shorting to ground? Thanks in advance!

 

[Bali]

Sounds like the next step is to uplug the IHKA and probe the four wires from it to the AUC connector.

 

[itscoo2pyopants]

I had the “auc heating” code come up on my 2004 325ci. I purchased a brand new sensor and cleared the code. Hasn’t came back after weeks of driving. It could be that you just need a new sensor.

 

[scottjoh]

The sensors have a limited life. It should be replaced with a BRAND NEW sensor. Don't buy 10+ year sensor that's already past it's life.

The part number for the replacement sensor is 64116917001. Currently $69.80 on the ECS Tuning web site.
Part number for the connector (to the AUC sensor) is 61138365356 and the part number for the crimp pin with wire is 61130005199.

 

[mikeypx82]

Sounds like the next step is to uplug the IHKA and probe the four wires from it to the AUC connector.

I was thinking the same thing. I'm going to do that today. If the wires are shorting to ground I think I'm going to have to make my own wire harness. My plan is to buy an extra 4-pin connector so I can plug the AUC into the IHKA from inside the car to test it out first. I'm still looking for the part # for the connector.