How do I fix my Toyota P0171?

STEP 1: USE FIXD TO ENSURE NO OTHER ENGINE CODES ARE PRESENT.
STEP 2: INSPECT VACUUM LINES.
STEP 3: INSPECT MASS AIR FLOW (MAF) SENSOR.
STEP 4: INSPECT EXHAUST SYSTEM.
STEP 5: CHECK FUEL PRESSURE.
STEP 6: REPLACE AIR-FUEL AND/OR O2 SENSORS.
STEP 7: INSPECT AND REPLACE SPARK PLUGS.

How do I reset P0171?

Table of Contents

Fixing a Check Engine Light (P0171)

Step 1: Purchase a OBD 2 Bluetooth Scanner.
Step 2: Insert the Scanner Into the OBD 2 Port of Your Car.
Step 3: Run a Diagnostic Scan.
Step 4: P0171.
Step 5: Removing the Mass Air Flow Sensor.
Step 6: The MAF Sensor.
Step 7: Clean the Sensor.
Step 8: Clear the Code.

What is code po171 mean in Toyota?

Oftentimes, a P0171 means that your Toyota is having trouble with a dirty or faulty mass airflow (MAF) sensor, or a vacuum leak downstream of the MAF sensor (perhaps in the PCV line or in the valve itself). Of course, this code can also signify a bad O2 sensor in bank 1.

What causes system too lean?

The lean condition can be caused by a vacuum leak, which introduces more air into the air-fuel mixture, or by a weak fuel system, which does not input enough fuel into the air-fuel mixture.

Can a bad O2 sensor cause a P0171?

When the ECM/PCM is having to add too much fuel based on input from the O2 sensor, the fault code P0171 will be sent to the ECM, which will trigger the check engine light to illuminate. This code could either mean that the oxygen sensor is detecting too much oxygen or too little fuel in the mixture.

Can a bad 02 sensor cause a lean code?

You probably know that the answer the questions is — no! A P0171 or P0174 lean code with an O2 sensor reading lean all the time mean — well, several things. The real problem may not be a bad O2 sensor, but possibly be an engine vacuum leak, low fuel pressure or dirty fuel injectors that are causing the engine run lean.

What causes P0171 and P0174?

P0171 is triggered by the engine bank 1 “upstream” oxygen sensor and P0174 is triggered by the engine bank 2 “upstream” oxygen sensor. The oxygen sensor alerts your system when the condition is too lean meaning there’s too much oxygen in the exhaust.

What causes a lean code on a Toyota Corolla?

If you see a lean code on this year Corolla, it is usually caused by a faulty oxygen sensor in front of the converter or an air/vacuum leak. Note: Also, verify the evaporative purge solenoid is not stuck open or being grounded all the time by the Engine Control Module (ECM).

Why does my Toyota Corolla not Hiccup while driving?

The problem may be on a much smaller scale where the computer on the Toyota Corolla can compensate for the lean condition and the driver may never feel a hiccup while driving. I will go over some of the more common ones I have seen on a Toyota Corolla and even the Toyota Matix as they use the same 4 cylinder engine.

Does a 1998 Toyota Corolla have a mass air flow sensor?

Note: While this code is common on 1998 – 2006 Toyota Corolla’s with a 1.8 liter engine, there are some older Corolla’s that still flag this code but do not use a mass air flow sensor. Instead, they use a MAP sensor. For example, a 1998 Toyota Corolla uses a MAP sensor intead of a MAF sensor.

What is the p0133 diagnostic trouble code on a Toyota Corolla?

Note: If you only have a P0133 diagnostic trouble code stored in your computer, there is another TSB that was released by Toyota for this code on Corolla’s and Matrix’s. The PCM Logic been modified to improve this condition. In other words. the fix is to recalibrate the main engine computer.