I have the P0030 code set on my new model V70 2,4 turbo 2000.
Is this the front sensor? (before the cat)
Is there any other possible cause exept for wiring for this code to be set.
I also have the P0128 Coolant Thermostat Coolant temp below Thermostat regulating temp set (time to change the thermostat).

Is it the heater in the sensor that has gone bad?
Can I check the oxygen sensor, what should I check for, short circuit?, open? any specific values?

Changed the Oxygen Sensor today.
All tests completed and no DTC´s set.
It was the heater in the sensor that was broken.
If you have DTC P0030 set, measure the resistance
between terminal 3 and 4 (middle terminals) in the
connector for the front sensor.
The reading skould be 3 ohm if it is ok otherwise open circuit.

Thanks for the help.

Yes, that is bank one sensor one, that means it is the front sensor. It has detected the heater circuit as being bad. You could check resistance through the circuit, what the spec is I have no idea. That car is late model enough that it should have a broad band sensor or what other manufacutrers refer to as an air fuel ratio sensor. It works much like on O2 sensor except it is much much faster, so much faster that when you view it all you should see is 1 volt. If it is still an old school sensor then you want to see that it can go from .1-.9 and that it can do this in 100 milliseconds or less. To test it properly you really need an oscillioscope and a propane enrichment kit. If it is the later model sensor you really need Vadis to check it out. I am sure there are other scanners out there that can plot the sensor but the factory tool does such an awesome job. If it is posting a code for it you probably need to hang a new sensor and put in the upgraded adapter harness.

Mark

Thanks I will check the harness and connectors tomorrow.
The fuse was ok and I had voltage on the fuse.
I have heard that it is unusual with Oxygen sensor failure
and that it often is the connector that is the the problem.
The heater circuit should be no problem to check, the fuse is 20 A
so it gives me a hint for the resistance value.

Now I have checked the Oxygen Sensor Heater and I
have open circuit between terminal 3 and 4.
According to the documentation it should be 3 ohms.
Can anyone confirm that the oxygen sensor heater on the front sensor is located at terminals 3 and 4 on a 2000 new model V70 2,4 turbo?

Any other suggestions?