1999 Toyota 4Runner V6 Engine P0171 Code: Diagnosis and Solutions

Model: 1999 Toyota 4 Runner Fault Code: P0171 Posted: 2013-06-09 12:39

I'm experiencing a recurring P0171 code on my 1999 Toyota 4Runner with the V6 engine. I've already performed several troubleshooting steps including cleaning the MAF sensor, checking the O2 sensor for Bank 1, completing a full tune-up with new spark plugs and harness, replacing the fuel filter, using fuel additive (for injector cleaning), conducting a smoke test (no leaks found), installing a new air intake filter, and verifying that fuel pressure is within normal range. All standard checks have been completed without identifying any issues. Despite these efforts, the P0171 code continues to appear. What other diagnostic steps should I consider to resolve this problem?