Trouble Code P0171

Don't know what kind of vehicle it is, but we see that code from time to time on 4runners and tacomas, and the usual culprit is the mass airflow sensor. Sometimes it's just a matter of removing debris from the sensing wire, sometimes it requires replacement.

What model & year

Sorry guys. I forgot to mention it is a 2001 4-Runner with the V-6.

It'll be just downstream of the airfilter, facing the passenger fender held in by two small phillips head screws. I think that it my be obstructed by the ABS valve body, this I can't remember for sure.

Trouble Area
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)
ECM

1 Check air induction system NG Repair or replace. OK 2 Check injector injection NG Replace injector. OK 3 Check mass air flow meter and engine coolant temperature sensor NG Repair or replace. OK 4 Check for spark and ignition NG Repair or replace. OK 5 Check fuel pressure NG Check and repair fuel pump, pressure regulator, fuel pipe line and filter OK 6 Check gas leakage on exhaust system. NG Repair or replace. OK 7 Check output voltage A/F sensor (bank 1 sensor 1). OK Go to step 9. NG 8 Check for open and short in harness and connector between ECM and A/F sensor (bank 1 sensor 1) NG Repair or replace harness or connector. OK Replace A/F sensor. 9 Perform confirmation driving pattern Go 10 Is there DTC P0171 or P0172 being output again? YES Check and replace ECM NO 11 Did vehicle runs out of fuel in past? NO Check for intermittent problems YES DTC P0171 or P0172 is caused by running out of fuel.

Thanks Guys!!

o2 sensor on Toyota Tundra typically.