# Check Engine light on

**URL:** <https://community.cartalk.com/t/check-engine-light-on/25877>\
**Category:** Maintenance/Repairs\
**Created:** [February 1, 2009, 6:09pm UTC](https://community.cartalk.com/t/check-engine-light-on/25877 "2009-02-01T18:09:54Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![enarch2](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@enarch2](https://community.cartalk.com/u/enarch2)\
**Post date:** [February 1, 2009, 6:09pm UTC](https://community.cartalk.com/t/check-engine-light-on/25877/1 "2009-02-01T18:09:54Z")

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I have 99 Merc. Grnd. Marq., code 0174 know showing up on the scanner, I also had 0171. I have done a vacum test and holding 21.5 Hg, I have change all rubber vacum hoses even if they did not need changed. I even changed the gromet for the PVC Vale on the right valve cover. Checked the injectors and all are clicking. I had changed spark plugs earlier and show a normal firing color. I had changed the fuel filter(last week) and MAF sensor a month ago. do I need to change the MAF sensor again. Lost?