P0171 & P0420

Beat me to it...

 

Hmm.. If I'm going uphill at highway speeds the lng trl will sit around 25-30 until I'm off the throttle. Temps are normal and power seems normal. I'm trying to baby it as much as I can as I make my way home.

 

I’ve had both of these codes. Ended up being related to small exhaust leak in the header and the exhaust pipe near the 1st O2 sensor. And the O2 sensors.

I checked for the obvious by using a really bright flashlight at night and looking out for smoke. And by using the Chrisfix method of soap/water spray. https://www.youtube.com/watch?v=N-exs1iMLFU

I’m pretty sure p0420 was due to my rear O2 sensor being out. Make sure to only replace these with Denso sensors from a reputable seller since there are a lot of threads of non-OEM and counterfeit-eBay sensors causing headaches.

good luck

 

My thought is verify the maf is working and reading correct. If the maf is reporting more airflow or less airflow than the engine is truly using it could cause the ecu to think its running lean/rich based on what its getting from the maf. But I could be wrong. Im still learning slowing learning how maf systems work

 

i had both 0171 and 0420. It turned out to be a combination of a small exhaust leak, as well as a dirty maf. That being said, I drove the truck with those codes on for literally 110,000 miles without any issues whatsoever. Not a recommendation, but just saying that I wouldn’t lose sleep over trying to fix it on the road.