# Po135 codes **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** heating, sensors, lexus, engines, 300\ **Created:** [November 3, 2009, 12:28am UTC](https://community.cartalk.com/t/po135-codes/38975 "2009-11-03T00:28:39Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![jimboandfam](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jimboandfam](https://community.cartalk.com/u/jimboandfam)\ **Post date:** [November 3, 2009, 12:28am UTC](https://community.cartalk.com/t/po135-codes/38975/1 "2009-11-03T00:28:39Z")
Our ?95 Lexus ES300’s, check engine light came on, though it still runs well. Our mechanic’s computer read code po135, so he changed the Oxygen sensor. Later that day, the check light came back on, so we decided the first sensor must have been bad, so we waited for a NEW O2 sensor and replaced it. Later THAT day, the check engine light came back on. Also that SAME day, our ?01 Honda Odyssey?s check engine light come on and started running rough! It shows the same po135 code! What is causing all the po135 codes?!? The FULL MOON?!? Our mechanic is baffled and we?ve ruled out bad gas and loose gas caps. ---
**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:** [November 3, 2009, 12:37am UTC](https://community.cartalk.com/t/po135-codes/38975/2 "2009-11-03T00:37:38Z")
This code indicates a problem with the heater circuit for that oxygen sensor. There are three things that can cause this code. The heater in the oxygen sensor is defective. But you’ve already tried replacing the oxygen sensor so that’s not it. There’s an open or short in the wiring for the oxygen sensor heater circuit. Or there’s a problem with the computer. Tester ---
**Author:** ![jimboandfam](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jimboandfam](https://community.cartalk.com/u/jimboandfam)\ **Post date:** [November 3, 2009, 12:44am UTC](https://community.cartalk.com/t/po135-codes/38975/3 "2009-11-03T00:44:53Z")
Thanks! We’ll check them and let you know. ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [November 3, 2009, 12:46am UTC](https://community.cartalk.com/t/po135-codes/38975/4 "2009-11-03T00:46:34Z")
Troubleshoot the oxygen sensor HEATER circuit with a wiring diagram and a multimeter. Measure resistances and voltages in the O2 HEATER circuit. This article gives a little more detail: [http://www.obd-codes.com/p0135](http://www.obd-codes.com/p0135) ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [November 3, 2009, 12:46am UTC](https://community.cartalk.com/t/po135-codes/38975/5 "2009-11-03T00:46:54Z")
Is the heater circuit fused? Maybe someone put a PO135 HEX on you…Maybe you need a Tarot Card reader, not a mechanic…