# Replaced both rear O2 sensors...still throwing B2 S2 dead code



## Bahnburner (May 31, 2000)

It's also saying B1 S1 and B2 S1 internal resistance too high. What could be causing that?


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## GLS-S4 (Jun 6, 2005)

*Re: Replaced both rear O2 sensors...still throwing B2 S2 dead code (Bahnburner)*

Which DTC for B2S2 ?
Perhaps try switching BxS2 connectors and see if code follows or not.
As for the second issue, suggest get the O2's pinouts and perform a ohm measurement on each sensor heater.
2.7T (and others) will trap "internal resistance too high" DTC's for both sensors per pair when only one may be out of spec. The Motronic system does not measure individual O2 heater circuit current but instead only measures total heater current draw in pairs as per BxS1 pair and BxS2 pair.


_Modified by GLS-S4 at 3:01 PM 5-26-2009_


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## Bahnburner (May 31, 2000)

*Re: Replaced both rear O2 sensors...still throwing B2 S2 dead code (GLS-S4)*

So, the internal resistance is in reference to the heater circuit only? I plan to do a Vag-com session and see what's happening...from there, I might remove and torch them for a test.


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## GLS-S4 (Jun 6, 2005)

*Re: Replaced both rear O2 sensors...still throwing B2 S2 dead code (Bahnburner)*


_Quote, originally posted by *Bahnburner* »_So, the internal resistance is in reference to the heater circuit only?

Yes.

No need to remove and torch, easier to ohm test at the firewall connector. You will know real quick which O2 has an open heater circuit. A good O2 heater will read low ohms and a failed heater will read very high ohms or open circiut.
Which DTC is coming from B2S2? Again switch BxS2 connectors at the firewall, drive and VAG Scan to see if DTC follows and go from there.


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## Bahnburner (May 31, 2000)

*Re: Replaced both rear O2 sensors...still throwing B2 S2 dead code (GLS-S4)*

Switched out sensors...still giving B2 S2 dead...I guess the problem is upstream in the harness or ECU.


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## Bahnburner (May 31, 2000)

*SOLVED Re: Replaced both rear O2 sensors...still throwing B2 S2 dead code (Bahnburner)*

After concluding that the wiring harness or ECU was faulty and not the O2 sensor, I began by peeling back the rubber boot where it connects to the sensor harness, and immediately could see that one of the wires had detached from the terminal...removed and installed repair terminal connector and problem solved. Cleared codes and all is well. http://****************.com/smile/emthup.gif


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