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P0174 Trouble Code – System Too Lean

In OBD2 Trouble Codes by Magnus SellénLeave a Comment

reset check engine lightThe P0174 trouble code can be a real pain because it can be pretty difficult to locate the problem.

But with the help of this article, you will be able to locate the problem quickly.

Basically, trouble code P0174 means that there is a lean mixture in your engine that needs to be repaired to get rid of the check engine light. Let’s go!

What Does the P0174 Code Mean?

Ideally, the combustion engine maintains the air-fuel mixture ratio of 14.7 parts air to 1 part fuel. This is the perfect ratio for the combustion engine to work effectively.

However, if there is too much air and the amount of fuel is not sufficient, a “lean” condition is created, which basically indicates that there is not enough fuel in the air-fuel mixture. As soon as the engine control module detects a lean condition, it triggers error code P0174.

The P0174 is a generic powertrain code and may trigger in any OBD2-equipped vehicle.

P0174 Trouble Code Symptoms

  • Check engine light starts to blink
  • Engine is incapable of producing enough power
  • Engine has trouble idling
  • Engine starts jerking
  • Engine starts to misfire

There are some cases where the driver might not feel any symptoms at all.

P0174 Trouble Code Possible Causes

Here are some of the common causes which trigger the P0174 trouble code:

  • Vacuum leak
  • Damaged or dirty mass airflow sensor (MAF)
  • Dirty or damaged fuel filter
  • Weak fuel pump
  • Clogged or worn out fuel injector
  • PCM software needs an upgrade
  • Faulty oxygen sensor
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Possible Solutions to fix the P0174 Trouble Code

Whenever the error code P0174 is generated, many drivers make the mistake of replacing the O2 oxygen sensor. It is recommended that you perform proper diagnostics before replacing any part to avoid wasting your hard-earned money. Here are some possible solutions to correct error code P0174:

How to Diagnose the P0174 Code?

Before you take your car to a mechanic for a checkup, here are some easy steps you can take to diagnose the P0174 trouble code.

Attach the Car Battery Charger

Bluetooth OBD2 scanner

When diagnosing error code P0174, it is important that you have connected the car battery charger, as diagnosing the error code is a lengthy procedure and there is a possibility that your car battery will be drained. This may generate additional error codes and cause further problems.

Connect the OBD2 Scanner

To ensure that there is something wrong with the air-fuel mixture, you can check whether the P0174 error code is generated by the vehicle’s onboard computer. To check if the code is triggered, connect the OBD2 scanner and scan to see exactly what the problem is.

Check for Vacuum Leak

Leaks in the vacuum hose or vacuum lines can cause unmetered air to enter the engine and disturb the air-fuel mixture. Inspect the vacuum lines and see if there are signs of damage. A damaged seal can also cause a vacuum leak and should be repaired as soon as possible.

Check out this article to find vacuum leaks.

Check the Mass Air Flow Sensor

If you have checked the vacuum lines and hose and have not found a problem, the problem may be with the air mass flow sensor. A dirty or damaged air mass flow sensor may not work effectively and would tell the engine that less air is entering the system. In such a case, cleaning the air mass flow sensor would solve the problem. The best way to clean the MAF is to use an electronic cleaner or brake cleaner, but be careful not to use too much force when cleaning as this could damage the sensor.

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How to test the Mass Air Flow Sensor

The best way to test the air mass flow sensor is to use a scan tool. The mechanic will measure the readings of the air mass flow sensor at various speeds using the readings of a new air mass flow sensor.

The air mass flow sensor is tested at idle, 1000 rpm, 2000 rpm, and 3000 rpm, and the measured value is measured. Normally, a dirty or worn airflow sensor will show a low airflow reading compared to a brand new sensor. Sometimes the low airflow reading does not necessarily mean that the airflow sensor is damaged. It may also be caused by a dirty air filter or a damaged catalytic converter.

Check the O2 Oxygen Sensor

In addition to the air mass flow sensor, the O2 oxygen sensor can also trigger error code P0174. If the oxygen sensor fails, it does not provide the correct information about the oxygen entering the system, which disturbs the air-fuel mixture ratio and thus triggers error code P0174.

Can I fix the P0174 Trouble Code Myself?

Since we have discussed that there are several reasons why the P0174 trouble code is generated by the vehicle’s onboard computer, some of the problems can easily be solved at home, while others require professional help. For example, if the problem is with the airflow meter, you can easily remove it and service it yourself.

Replacing a clogged air filter is also easy and could be done at home. However, if there is any other major problem with the engine’s intake system, it is recommended that the vehicle be subjected to a professional inspection.

How Serious is the P0174 Trouble Code?

If your vehicle does not get the right air-fuel mixture, there is a chance that the engine will not perform optimally and start to cough. If the problem is not corrected over a long period of time, it can cause serious damage to the engine and you will end up paying a lot of money for engine repair.

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Further Questions?

If you have another specific question regarding the P0174 fault code or your vehicle, please write it down below and one of our professional mechanics will help you.

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

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