Hi all,

I have a 2008 F150 5.4 V8 that I have taken wheeling twice. Both times ended with the check engine light. The first time was after we splashed through a muddy section of the road (back & forth a few times). Three cold starts later the light shut off so I thought it was from the electrical panel getting wet. Yesterday, I took it up to approximately 10k feet and wheeled in the snow. This led to the check engine light again after we got stuck in a little snow, backed it up a few times to get a run at it.

Firestone provided me with the 3 following codes: PO171, PO301, and PO316. They are suggesting a tune up. My brother says they are all based around the master airflow sensor and/or faulty plug/plug wire.

What do you all think my first step should be?

Thanks,
Kris