# O2 Sensor Voltage **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [October 19, 2007, 7:00pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282 "2007-10-19T19:00:55Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![timo](https://avatars.discourse-cdn.com/v4/letter/t/c4cdca/32.png) [@timo](https://forums.speedlife.net/u/timo)\ **Post date:** [October 19, 2007, 7:00pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/1 "2007-10-19T19:00:55Z")
Looking to not replace downstream 02 sensor (after cat). Wonder if anyone would know this- can I feed a voltage to the ECU from the 02 sensor lead that would keep a fault code, and check engine light from occuring? Would the impedance matter? What voltage would I need? Car is '97 Ford Aspire and I’d rather not spend the $250+ for a new 02 sensor. ---
**Author:** ![HotRodKid](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/hotrodkid/32/7609_2.png) [@HotRodKid](https://forums.speedlife.net/u/HotRodKid)\ **Post date:** [October 19, 2007, 7:11pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/2 "2007-10-19T19:11:49Z")
the downstream sensor, because its after the cat, has a different output then the upstream sensor splicing into the upstream sensor will basicly tell the ECU that the cats doing nothing, because both voltages now match replace the sensor or get a chip which turns it off ---
**Author:** ![timo](https://avatars.discourse-cdn.com/v4/letter/t/c4cdca/32.png) [@timo](https://forums.speedlife.net/u/timo)\ **Post date:** [October 19, 2007, 7:55pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/3 "2007-10-19T19:55:28Z")
So, If the voltage threshold that the ECU likes is different from the upstream sensor, can’t you just feed a voltage that is within that threshold? ---
**Author:** ![RacerX](https://avatars.discourse-cdn.com/v4/letter/r/5e9695/32.png) [@RacerX](https://forums.speedlife.net/u/RacerX)\ **Post date:** [October 19, 2007, 7:59pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/4 "2007-10-19T19:59:27Z")
The ecu is looking for a change in the voltage corrosponding to but not matching the upstream to see if the convertor is working. There are a myriad of O2 simulators available aftermarket for performance reasons. If you are just trying to solve a CEL issue then you have to replace the sensor, buy a simulator or replace the cat if it’s non-functioning ---
**Author:** ![HotRodKid](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/hotrodkid/32/7609_2.png) [@HotRodKid](https://forums.speedlife.net/u/HotRodKid)\ **Post date:** [October 19, 2007, 8:03pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/5 "2007-10-19T20:03:04Z")
^^ and thats not nearly as easy as it sounds the best bet is a o2 sim, but good ones are $100 and dont always work, alot of cars are smarter then that ---
**Author:** ![reliant\_turbo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/reliant_turbo/32/7189_2.png) [@reliant\_turbo](https://forums.speedlife.net/u/reliant_turbo)\ **Post date:** [October 19, 2007, 8:09pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/6 "2007-10-19T20:09:06Z")
some folks have good luck with screwing two spark plug non-foulers into the second o2 hole and then the sensor into the non-fouler. cheap and easy test to see if it will work. Brian ---
**Author:** ![HotRodKid](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/hotrodkid/32/7609_2.png) [@HotRodKid](https://forums.speedlife.net/u/HotRodKid)\ **Post date:** [October 19, 2007, 9:14pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/7 "2007-10-19T21:14:23Z")
^^^ but thats for people w/o converters …hes without a rear o2 sensor … meaning hes got to GET a rear o2 to do the trick … but he doesnt have to do the trick because he still has a converter, lol ---
**Author:** ![reliant\_turbo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/reliant_turbo/32/7189_2.png) [@reliant\_turbo](https://forums.speedlife.net/u/reliant_turbo)\ **Post date:** [October 20, 2007, 11:59am UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/8 "2007-10-20T11:59:31Z")
oops, i guess i didnt read lol ---
**Author:** ![cougarspeed](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/cougarspeed/32/7468_2.png) [@cougarspeed](https://forums.speedlife.net/u/cougarspeed)\ **Post date:** [October 20, 2007, 12:07pm UTC](https://forums.speedlife.net/t/o2-sensor-voltage/37282/9 "2007-10-20T12:07:21Z")
O2 SIM FTW!!!