# 1999 Honda Civic Oxygen Sensor "PO-135"

**URL:** <https://community.cartalk.com/t/1999-honda-civic-oxygen-sensor-po-135/21191>\
**Category:** Maintenance/Repairs\
**Tags:** engines, lights\
**Created:** [October 25, 2008, 2:33am UTC](https://community.cartalk.com/t/1999-honda-civic-oxygen-sensor-po-135/21191 "2008-10-25T02:33:33Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mharrigan](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@mharrigan](https://community.cartalk.com/u/mharrigan)\
**Post date:** [October 25, 2008, 2:33am UTC](https://community.cartalk.com/t/1999-honda-civic-oxygen-sensor-po-135/21191/1 "2008-10-25T02:33:33Z")

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This code came up (PO-135) and when I pulled the exhaust manafold heat shield I found that the manafold was slightly cracked - so I replaced it (which includes the cat) and the OS (the one before the cat) and reset the check engine light with my code reader, but it keeps coming back on - what now?

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**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\
**Post date:** [October 25, 2008, 2:39pm UTC](https://community.cartalk.com/t/1999-honda-civic-oxygen-sensor-po-135/21191/2 "2008-10-25T14:39:54Z")

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I assume you mean code P0135. That code indicates there is a problem with the O2 sensor heater circuit. The heater element is either bad or there is a problem with the circuit to the heater element.

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**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\
**Post date:** [October 25, 2008, 3:59pm UTC](https://community.cartalk.com/t/1999-honda-civic-oxygen-sensor-po-135/21191/3 "2008-10-25T15:59:27Z")

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Here is a link to a little detail of what causes a DTC code P0135 to show up: [http://www.obd-codes.com/p0135](http://www.obd-codes.com/p0135)  
Since there was a crack in the exhaust manifold, the hot exhaust may have damaged the oxygen sensor wires and connector. Examine them.  
Here is a link to a post right here at cartalk: [http://community.cartalk.com/posts/list/21/1735010.page](http://community.cartalk.com/posts/list/21/1735010.page) It explains how to check oxygen sensor heater(s) (and the PCM control when a scan tool, or a inductive clamp-on amp meter is used).