Diagnostic or Troubleshooting Tree

[wreckerboy]

I am looking for a diagnostic or troubleshooting tree to allow me to verify the cause of the P0171 code I am seeing. ('00 'rolla)

I know from searching here that the most likely causes are either a bad MAF sensor or a oxygen sensor output issue. I'll verify that diagnosis tonight by looking at the O2 output with my scanner and by checking the MAF per Haynes. However, I would like to know how that conclusion (diagnosis) was reached. Thus, the hunt for a troubleshooting tree. Also, in the (admittedly unlikely) event I have other issues with the car in the future it would be a handy troubleshooting aid.

Can anybody point me in the right direction? TIA

(Forgive the use of terms like "troubleshoot" "diagnosis" and diagnostic" - I'm just trying to make things easier for somebody searching on this subject in the future.)

[noahedvalson]

I have a 2000 Corolla with the P0171 code coming already (73K miles). I cleaned the MAF sensor, but the code came back. I am just wondering what you ended up doing to solve yours???

[wreckerboy]

As you did, we cleaned ours and that cleared the code for a few days and less than 100 miles. We ended up replacing it and haven't had the code since.