P0140 - 02 sensor no activity detected?

[upallnight]

Originally Posted by s14dk

thanks for the info. greatly appreciated.

so when i test the oxygen sensor itself , should I be looking for voltage or resistance?

and when i test the factory harness that connects into the oxygen sensor what type of reading should i expect?


sorry for the newb questions.

Using a digital volt meter you can measure the voltage generated by the 02 sensor when you apply heat to the tip of the 02 sensor. There's plenty of Youtube videos on how to test 02 sensors.

[Rockabilly Rebel]

Hi guys,
my '05 E53 N62 is shooting P0140 & P0141 codes - So what I understand from that is that Bank 1 (Right side) Sensor 2 is malfunctioning.

Yesterday I removed the sensor, let the tip soak in gas, checked the connection, and put a tester/light on the incoming 4 wire harness.

Once I start up the car and get under to check for power, (with the O2 sensor unplugged) only 1 wire is getting power, the other 3 show no electric current. I checked on bank 2 and I get the same thing; only 1 live wire. Is this normal and just proves that I need a new sensor? Or do I have other 'upstream' electric issues? Or is it possible that a second wire is getting power but not enough to light up the bulb on a test light?

Any help would be cool. Thanks in advance.

[80stech]

Yes, that is correct. 2 wires are grounds, one wire is the power for the heater and the senor wire will not lite a test lite.

[StephenVA]

You should only be using a DVM on an O2 sensor as the readings are way low in volts

Great read on O2 sensors (we have Lamda A/F sensors)
"The following are known good voltages for air-fuel sensors compiled over the last few years: 3.3 V (Toyota), 2.8 V (Honda), 1.9 V (Hyundai), 2.44 V (Subaru), 1.47 V (Nissan), 1.00 Lambda (all European manufacturers). Remember that a 1.00 Lamda is perfect while any movement above 1.00 (i.e. 1.01) is one perfect lean, and any movement below is rich by the same proportion. For example, a Lambda of 0.85 might set a system rich DTC with a LTFT of – 15%. Companies are not always forthcoming with this information, so you will have to compare voltages with known good vehicles in your shop."

https://www.autoserviceprofessional....agnosis?Page=3

[Rockabilly Rebel]

Thanks for your help guys. I replaced the O2 sensor and Perfect! Code went away.