P0171

[AZ3rdGenRunner]

well...

Well... Did that fix your CEL?

Mine has come on again and again!

Replaced a bunch of vacuum hoses, cleaned the MAF sensor as thoroughly as I clean any of my firearms! Checked my O2 sensors and both seem fine!

I cannot figure it out!

I have a new MAF on order (despite dearleship saying it is in perfect working order), new O2 sensors (upstream and downstream), new air filter, new spark plugs, and plug wires! Hoping this will fix the CEL!

'99 Limited 4x4 E-Locker

 

[TheDurk]

Well... Did that fix your CEL?

Mine has come on again and again!

Replaced a bunch of vacuum hoses, cleaned the MAF sensor as thoroughly as I clean any of my firearms! Checked my O2 sensors and both seem fine!

I cannot figure it out!

I have a new MAF on order (despite dearleship saying it is in perfect working order), new O2 sensors (upstream and downstream), new air filter, new spark plugs, and plug wires! Hoping this will fix the CEL!

'99 Limited 4x4 E-Locker

You don't mention:

Clean throttle body (cured mine once, early on, before I had learned to do it on a regular basis)
Check or replace PCV
Check carefully for exhaust leaks

Here is the official list:

DTC No. DTC Detecting Condition Trouble Area
P0171
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on RICH side
(2 trip detection logic):


Air induction system

Injector blockage

Mass air flow meter

Engine coolant temp. sensor

Fuel pressure

Gas leakage on exhaust system

Open or short in A/F sensor (bank 1 sensor 1) circuit

A/F sensor (bank 1 sensor 1)

PCV valve and hose

ECM

 

[kingin]

I'm fighting similar issue with p0171 on my 96 4runner 3.4 swapped mafs from salvage yard vehicle no change replaced front 02 with denso still cel back. Unlike guys with 99+ 4runners my MAF isn't 200 bucks new from dealer.

 

[ridefast]

Now i am wondering if you found out what was wrong?

 

[Grapejuicepapii]

2000 SR5 p0171 and P1130 codes

Hey everyone really needing some help here stumped on this lean code
Took it to a good reviews mechanic and He just screwed me

I’ve had a p0171 code for awhile
Took it to a mechanic he said I had one bad fuel injector and replaced just that one for the price of 6 of them ���� (I respect paying for experience and good work) but he didn’t fix the problem

Since then I’ve ran multiple fuel injector cleaners
Replaced my fuel filter and recently replaced my bank 1 sensor 2 o2 sensor I was also getting a code for that and tested it and it was bad

That code has gone away and just today a bank 1 sensor 1 has come up and the same p0171 lean code

Looking to fix it next time I throw money at it anyone have any ideas? Any thoughts are greatly appreciated or just point me to the right thread please

2000 Toyota 4Runner SR5

 

[jgue467]

... stumped on this lean code
Took it to a good reviews mechanic and He just screwed me

I’ve had a p0171 code for awhile ..

Yeah get Another 'mechanic'.

0171 means it is too lean but not necessarily cuz there is not enough fuel but the contrary. There is too much Air.

Check all the rubber tubing from air filter to the metal intake.

Mine had a crack underneath where it can't be seen easily on the last large tube before the metal intake, go with OEM toyota parts for long lasting repairs.

Here's a pic of what I replaced on my 01.

Luck.

 

[Captsolo]

Troubleshooting P0171 Code. Oftentimes, a P0171 means that your Toyota is having trouble with a dirty or faulty mass air flow (MAF) sensor, or a vacuum leak downstream of the MAF sensor (perhaps in the PCV line or in the valve itself). Toyota Parts | P0171 Diagnostic Code - Trouble Code Diagnosis Guide

 

[Devbot]

O2 sensors or vacuum leak will cause P0171 the majority of the time if not the MAF, try finding a leak first since it's the cheaper of the two. I'm willing to put money down the stealership knows this full and well - P0171 is one of the most common codes for us and buying a new cat in general to tackle this problem, let alone as your first step, is utterly outrageous.
Edit: If your sensors weren't OEM, they could be faulty - always stick to Denso/Matsu on sensitive parts. Even though the hoses were replaced I'm sure it wouldn't hurt to try a puff or twelve of carb cleaner in the engine bay.