Stumped

2000 SR5, 2.7L, 4x4 X-Cab
Codes P0171
Parts replaced: Upstream A/F Sensor, downstream O2 Sensor, MAF Sensor, Fuel Filter, Injectors, and finally the ECM and performed general tune up (spark plugs, Air Filter), and vacuum test. The only smoke I found was very minimal around the EGR valve regulator, so I ordered that now.

So I think I've replaced just about everything related to this code with the last swap being a true Denso A/F Sensor and still throwing codes - now inconsistent, meaning I'm now getting a P0110 - Air Temp Sensor 1, along with the P0171, & P1130 - A/F Sensor Circuit. I ordered and installed the BlueDriver which is truley amazing for $99!

I've ran road trips to plot Fuel Trims. Before the last Denso A/F swap I was getting High Trims ~ 19 - 30. After the new Denso A/F sensor swap and clearing ECM memory, I got much better fuel trims at first, but now getting high fuel trims again and throwing different random codes like the P0110.

The truck lived 10 years in Syracuse, NY so had lots of corrosion underneath. I'm thinking possibly the under hood wiring harness has maybe internal issue from salt laden environment? Has anyone actually seen a wiring harness go bad? I don't know where else to go next or try next...

 

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