# 2003 Mercedes-Benz C-Class

**URL:** <https://community.cartalk.com/t/2003-mercedes-benz-c-class/113829>\
**Category:** Maintenance/Repairs\
**Tags:** mercedes-benz, oil\
**Created:** [March 16, 2018, 6:43pm UTC](https://community.cartalk.com/t/2003-mercedes-benz-c-class/113829 "2018-03-16T18:43:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![John15](https://avatars.discourse-cdn.com/v4/letter/j/439d5e/32.png) [@John15](https://community.cartalk.com/u/John15)\
**Post date:** [March 16, 2018, 6:43pm UTC](https://community.cartalk.com/t/2003-mercedes-benz-c-class/113829/1 "2018-03-16T18:43:18Z")

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My 2003 Mercedes C-230 engine light came on just after it passed a registration emissions inspection. It was cleared out but came back. I checked the oil and a quart low, added oil, light still on. Had code checked and found it to be P0170 fuel trim (bank 1). What should I do, if anything?

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<div class="post-metadata">

**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\
**Post date:** [March 16, 2018, 8:35pm UTC](https://community.cartalk.com/t/2003-mercedes-benz-c-class/113829/2 "2018-03-16T20:35:51Z")

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The causes of a P0170 code

Any condition that causes the engine to run lean such as a weak fuel pump, a clogged fuel filter, or a faulty fuel pressure regulator

Any condition that causes the engine to run rich such as a mass air flow sensor, manifold absolute pressure sensor, or a faulty fuel pressure regulator

A faulty powertrain control module

Take it to your favorite independent mechanic and have them check for the code and then check for the cause of the code. If you keep driving with the code you could damage a piston by running too lean or damage the catalytic converter by running too rich. Both are expensive.