Saab 9-3 P0174: Fuel System – Lean (Bank 2) Diagnosis

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P0174 Saab 9-3

One of the most common trouble codes with the Saab 9-3 is the P0174 code. This code number references a number that is given to you when you plug your truck into a OBDII scanner. The code is often accompanied by the P0171 code, which has the same set of symptoms, but is for bank one. Bank 1 and Bank2 refer to the side of the engine with cylinder 1 and 2 in the firing order respectively.

 

Saab 9-3 P0174 Diagnosis

 

9-3 P0174 Code Defined

P0174 is an OBDII trouble code. It’s a general code, which means that it’ll have the same meaning regardless of who manufactured the vehicle (1996+)

The code is thrown when the oxygen sensors detect that there’s not enough oxygen in the exhaust system. This is commonly referred to as a “lean” condition.

The vehicle’s ECM will add more fuel to the mixture in order to bring the air fuel mixture where it needs to be for optimal combustion. It also throws the code P0174 to let you know that it has done this.

 

9-3 P0174 Code Symptoms

The P0174 code on a Saab 9-3 will often be thrown if the fuel injection system is not operating properly. Typically the code will be triggered by a lean condition in the engine.

There aren’t usually any drivability issues associated with P0174. For most people the first sign that anything is wrong at all is the service engine soon light coming on.

Here are the typical symptoms that something is wrong when you have code P0174.

  • Mileage- may or may not suffer depending on how much the air fuel mixture has changed.
  • Misfire– If the air fuel mixture has gotten too far from factory specs, this can cause the 9-3 to misfire.
  • Idle Issues– With the air/fuel mixture altered, the vehicle can idle erratically as the computer compensates to keep the engine running.

 

Saab 9-3 P0174 Causes

There are many things that can cause the P0174 trouble code on the Saab 9-3. Here are some of the most common issues:

  • Vacuum Leaks– With the Saab 9-3, the most common cause for the P0174 code to show is a vacuum leak. Take a look around and see if you can find the vacuum leak. Here’s a great YouTube video on how to find a vacuum leak.
  • Mass Air Flow Sensor– The mass air flow sensor calculates the volume of air entering the engine. If it has gone bad, the air fuel mixture will be off and the P0174 code will show. How to Check and Detect a bad Mass Airflow Sensor.
  • Bad Fuel Injectors– If you have one or more fuel injectors that have gone bad that can certainly cause the air/fuel mixture to go bad.
  • Fuel Pump/Fuel Filter– Today’s modern fuel injected motors need a lot of fuel pressure to atomize the gas properly. If the fuel pressure is not as high as it needs to be this atomization doesn’t happen properly and the optimal air/fuel mixture isn’t achieved. Unless you have a reason to believe this is the issue, don’t start here.
  • Bad O2 Sensors– There very well could be nothing wrong with the air fuel mixture at all. If the oxygen sensors are bad, it’ll erroneously throw P0174. In this case, the motor will begin to run too rich since the air fuel mixture was richened unnecessarily. This is often the cause of P0174. They are relatively inexpensive and easy to replace, and this often ends up being the problem.

Here’s a helpful video:

Good luck figuring out what is wrong with your 9-3. If there is anything that you feel could improve the article, please feel free to comment or message. Thank you.