# Maf? p0171 p0174

**URL:** <https://community.cartalk.com/t/maf-p0171-p0174/166414>\
**Category:** Maintenance/Repairs\
**Tags:** chevrolet, 1500\
**Created:** [June 26, 2020, 11:24pm UTC](https://community.cartalk.com/t/maf-p0171-p0174/166414 "2020-06-26T23:24:18Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Charlie-121](https://avatars.discourse-cdn.com/v4/letter/c/858c86/32.png) [@Charlie-121](https://community.cartalk.com/u/Charlie-121)\
**Post date:** [June 26, 2020, 11:24pm UTC](https://community.cartalk.com/t/maf-p0171-p0174/166414/1 "2020-06-26T23:24:18Z")

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my 2011 z71 ltz silverado cel came back on this morning after changing maf a couple weeks ago. a couple weeks ago it cel came on had the codes ran came back p0171 maf. switched it and reset it by pulling the battery. this morning it was back so I had the codes ran again. this time p0171 and p0174. brand new sensor k&n filter brand new. I tried pulling the sensors connection while running and truck stays on connecting and disconnecting. any ides what it could be maybe bad wire harness??

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**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:** [June 26, 2020, 11:30pm UTC](https://community.cartalk.com/t/maf-p0171-p0174/166414/2 "2020-06-26T23:30:02Z")

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We tested K&N filters at the company I retired from.

Results?

If you want to keep birds and chipmunks out of your engine, that’s the air filter to install.

Tester

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**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\
**Post date:** [June 26, 2020, 11:49pm UTC](https://community.cartalk.com/t/maf-p0171-p0174/166414/3 "2020-06-26T23:49:29Z")

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## What Causes the P0174 Code?

The most common causes of the P0174 code are the following:

- Vacuum leak due to damaged intake manifold gaskets or punctured vacuum and positive crankcase ventilation (PCV) hoses
- Malfunctioning mass airflow (MAF) sensor
- Clogged fuel filter
- Failing fuel pump
- Clogged fuel injectors
- Failing fuel pressure regulator
- PCM issues (e.g., software in need of an update)
- Worn-out oxygen sensor

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<div class="post-metadata">

**Author:** ![Charlie-121](https://avatars.discourse-cdn.com/v4/letter/c/858c86/32.png) [@Charlie-121](https://community.cartalk.com/u/Charlie-121)\
**Post date:** [June 26, 2020, 11:57pm UTC](https://community.cartalk.com/t/maf-p0171-p0174/166414/4 "2020-06-26T23:57:53Z")

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trying to narrow it down. I know when you have the vehicle running (most vehicles) disconnecting the maf will stall the engine. when i disconnect it stays running connecting and disconnecting while running. with a brand new maf sensor.

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**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:** [June 27, 2020, 12:05am UTC](https://community.cartalk.com/t/maf-p0171-p0174/166414/5 "2020-06-27T00:05:28Z")

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If you unplug the MAF sensor, the computer will substitute the lost signal with a default value programmed into the computer to keep the engine running.

> **[Car runs with the mass airflow sensor unplugged. If you p...](https://www.yourmechanic.com/question/car-runs-with-the-mass-airflow-sensor-unplugged-if-you-plug-it-in-it-will-die-if-the-car-is-running-by-slim-p)**
>
> Q: If you unplug the mass air flow sensor the car will start. If you try to plug it in while it's running the car will die. My car has 90000 miles. My car has an automatic transmission. This is a sure sign of a shorted mass...

Tester