# No Activity In My Oxygen Sensor **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** buick, century\ **Created:** [August 20, 2026, 5:21pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087 "2026-08-20T17:21:46Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 20, 2026, 5:21pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/1 "2026-08-20T17:21:46Z")
My 2000 Buick Century 3.1 L gave me a code 140. It was recently replaced with an exhaust system replacement and that’s when I got the 140 code. The old sensor had given me a code indicating a problem in the sensor heater circuit. I was going to remove new the sensor, bank 1 sensor 2, and check resistances between the input leads and compare with the readings found in a new sensor from AutoZone to see if I obviously have a bad new sensor in my car. And, I had found the red wire to the sensor connector broken and spliced it. After clearing the code, the code 140 came back after about 20 minutes driving. But this time I did not get a sensor heater control circuit code. What might be a common cause for this code 140? Could an ohmmeter tell me about the status of this sensor? Should I check voltages going into the sensor? What should the voltages be? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [August 20, 2026, 5:40pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/2 "2026-08-20T17:40:19Z")
[![](https://global.discourse-cdn.com/cartalk/original/3X/3/f/3f55dfa891f965738aca9be3c484e5401a4aaa45.jpeg "bench testing an oxygen sensor with a propane torch") ](https://www.youtube.com/watch?v=o6iXNBPPhwc) Tester ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 20, 2026, 6:38pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/3 "2026-08-20T18:38:23Z")
Tester, thanks for your reply, yet.the video doesn’t talk about which wires to connect to. Might you know which ones for a 2000 Buick Century 3.1L? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [August 20, 2026, 6:55pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/4 "2026-08-20T18:55:11Z")
The signal wire from the O2 sensor is purple with a white stripe. The positive lead of the meter connects there. The ground wire of the meter connects to the sensor itself. I usually connect on the metal where the wires of sensor enter the sensor. Tester ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 20, 2026, 8:59pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/5 "2026-08-20T20:59:23Z")
Thanks for this info ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [August 21, 2026, 12:02pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/6 "2026-08-21T12:02:49Z")
I got cheap o2 sensor. And got new different code. So I then got an Oem sensor and been good. ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 26, 2026, 7:16pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/7 "2026-08-26T19:16:13Z")
My scan tool.only gives me the code number which is described as no activity in this O2 sensor ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [August 26, 2026, 11:19pm UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/8 "2026-08-26T23:19:04Z")
> [@gudenteit](#): > > My scan tool.only gives me the code number It doesn’t give you live data? If so, you’ve got a code reader and you need to step up and buy a scanner ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [August 27, 2026, 12:33am UTC](https://community.cartalk.com/t/no-activity-in-my-oxygen-sensor/206087/9 "2026-08-27T00:33:58Z")
Inspect the oxygen sensor heater fuse in the under-hood fuse box. Then test for power to the O2 sensor heater. It is possible to have no power to the O2 sensor heater and fault detection is delayed.