# O2 sensor heater Circuit



## ursquattro (Jun 28, 2007)

2000 VW passat 30V 4motion-
Trying to figure out a problem-
First B2S2 heater circuit- sporadic DTC-
1)replace B2S2-
Car gives same code after new O2 sensor is installed-
2)Remove new o2 and replace with another(thinking it was a bad sensor)
Car gives same code again-after new sensor put in-again(and the code comes back within about a day-)
3)Check resistance in O2 sensor, all ok, check continuity in wiring to o2 sensor via connector-even give it a wiggle test while reading-no issues found. Check continuity and wiggle test wiring from ECU to connector on firewall. all ok-
Check for wanted voltage(fluctuating between 1-5V) at connector for o2-little to no voltage-(Voltage is to be streaming in highs and lows)
Go all the way back to the correct pins exiting the ECU and no voltage fluctuation there, ie no heater actuation in o2 sensor-
SOOOoooooooooo
4) Replace what was thought to be a faulty, the ECU-used ECU was found same part number etc etc(it is correct) and voila! ......same problem
At wits end----anywone else have the same problem?








Help is very appreciated


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## Slimjimmn (Apr 8, 2006)

*Re: O2 sensor heater Circuit (ursquattro)*

what sensor in relation to the engine did you replace driver or passenger front or rear?


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## ursquattro (Jun 28, 2007)

The sensor replaced was the drivers side rear-verified via ALLDATA-and it is indeed the correct one-


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