P0171 P0174 along with P0500

by MickyB
(Wisconsin)

Hello and thanks in advance for reading, I have a '03 4x4 v6 Highlander. Here is the short version. Will a P0500 code trigger a P0171-P0174. The engine is running rough and sputters at high speeds. Read on if you want more details.

Went on a 140 mile round trip last night in -5 cold weather doing an avg. of 70mph on the Interstate. My way there was fine but coming back about 4 hours later I noticed some engine sputtering. Kind of like I was loosing some HP or like I was running out of gas despite filling up partially through my trip. Stopped at a gas station to see if there was ice or snow in my tail pipe and check my fluids. All was good but when I turned on the truck, the check eng light came on. Back on the freeway I went and it seemed like the problem was getting worse. It wasn’t happening while decelerate but when I kept a continues speed. Also seemed like tranny was shifting fine. Got off again and put in some 93 oct. gas as I thought the prior fill up may have been dirty gas or perhaps the cold air temp./10% ethanol blend was a prob. I took side roads then back home and it seemed that I had no probs. going under 40mph. Today, I hooked up my OBD scanner and read PO171, PO174 & PO500. After my research on the lean mixture read, I see that I can check for a dirty MAF or MAP and a few other things that I may DIY. However the speed sensor research isn't going as well. I did find a post that the speed sensor malfunction could trigger the PO171/174 also but didn't get too much more than that....There was another post that I read about PO500 about the DYNO at the emissions triggered a PO500. I haven’t been on a DYNO at all but last week I did get stuck in a 2' snow covered ditch. I was stuck badly enough were I needed a little help from a pulling strap and an Outback AWD. After I got out of that mess(again on a trip), my check eng. light came on. However it went off half way through the trip after a gas fill. I didn't have my OBD scanner with me to check it out. But after that the truck seemed fine. So I don't know if that had anything to do with this recent problem or what. I thought maybe, if the speed sensors were thrown by some wheels spinning and other not while in the ditch. Kind of far fetch but who knows. Also I had my emissions test between incidents and I passed. Any help is greatly appreciated. Micky