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P0175 Code: Symptoms and How to Fix It! 

  • Cars Explained
  • Gerard Stevens
  • 5 minutes

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The engine runs lean when there is too much air or too little gasoline, resulting in P0171 or P0174 engine codes. In contrast, too much fuel or too little air causes the engine to run rich, resulting in the P0175 code and the check engine light turning on. It is one Diagnostic trouble code (DTC) that often appears in a car.  

A vacuum leak, which brings more air into the air-fuel mixture, or a poor fuel system, which does not inject enough fuel into the air-fuel mixture, can produce a rich state. To compensate for the lean state, the powertrain control module (PCM) pumps more fuel into the mixture to maintain the required 14.7:1 ratio. 

Be mindful that this code is very similar to P0172. So, what are the symptoms of the P0171 code? How can you fix it? Here’s all the info you need! 

What does code P0175 mean? 

The Engine Control Module (ECM) detects too much fuel and not enough oxygen in the air-fuel ratio (AFR), resulting in the P0175 code. The code activates when the ECM is unable to adjust for the amount of air or fuel required to return the air-fuel ratio to the established parameters. 

This diagnostic code shows up when the oxygen sensor in Bank 2 detects a very high condition, or there is inadequate oxygen in the exhaust gases. Bank 2 corresponds to the side of the engine with cylinder number 1 on 6-, 8-, and 10-cylinder engines. 

What can cause a P0175 code? 

These are the several factors that can cause the P0175 code to appear. 

  • A clogged or leaking fuel injector 
  • Fuel regulator failure 
  • A clogged or defective mass air-flow sensor 
  • Defective coolant temperature sensor  
  • Thermostat malfunction 
  • ECM requires reprogramming 
  • Unclean or faulty oxygen sensor 
  • Have vacuum leaks – PCV hoses, vacuum hoses, and the intake manifold gasket 
  • Issues with fuel delivery 
  • Inaccurate fuel pressure 
  • Leaking exhaust 

What are the symptoms of the P0175 code? 

It is very crucial to know the symptoms of this DTC. Since the appearance of this code can severely affect the lives of the engine and catalytic converter, you must diagnose the issue as soon as the symptoms appear. These are some of the common symptoms when the code activates.  

  • Check Engine Light turns on or flashes 
  • Engine lacks power 
  • Rough idling 
  • Engine starts misfiring  
  • Strong odor coming out from the exhaust 
  • Accumulation of dust on the spark plug diodes 


How serious is the P0175 code? 

An excessively rich system will force the catalytic converter to filter out more impurities, reducing the converter’s lifespan. The resulting increased gas consumption could be very costly. An incorrect air-fuel ratio causes the engine to work harder, reducing its lifespan. As a result, the engine will produce higher levels of dangerous pollutants. Be mindful that replacing a catalytic converter can turn out too expensive! 

Is it safe to drive with a P0175 code?  

The issues that come with a P0175 code do not make driving impossible. However, your car will become inefficient and may develop more serious problems when you ignore the code for a long period. When the air-to-fuel ratio tilts towards more gasoline, you’ll only get fewer miles per gallon. So, you need to fill up regularly when the code activates.  

How to diagnose P0175 code 

A skilled mechanic does these steps to diagnose the engine code.  

  • Inspect the fuel pressure 
  • Check for restrictions in the fuel injectors 
  • Inspects the fuel injector pulse  
  • Looks for pinches or cracks in the fuel lines 
  • Examines all vacuum lines for damage and cracks 
  • Check the oxygen sensors 
  • Reads the engine temperature with a scan tool, then compares the results to an infrared thermometer 

Common mistakes that happen while diagnosing 

  • Not measuring the temperature of the engine with a scan tool and comparing it to a thermometer 
  • Considering a component to be defective without testing it 

How to fix a P0175 code 

Once the mechanic diagnoses the issue, you need to fix the code by doing the following repairs. 

  • Replacement of broken or cracked vacuum lines 
  • Replacing or cleaning the O2 sensors  
  • Replacing or cleaning the mass air-flow sensor (MAF) 
  • Reprogramming the Engine Control Module (ECM) 
  • Replacing fuel pump 
  • Replacement of fuel filter 
  • Replacement of a defective or pinched fuel line 
  • Replacing a defective fuel injector 
  • Changing a broken thermostat 
  • Replacing a faulty coolant temperature sensor 

How much does it cost to fix code P0175? 

You need to do one or more of the following repairs to resolve the primary issue for the P0175 code. The estimated cost of repair for each likely repair includes the cost of the applicable parts as well as the cost of labor. The repair cost varies based on your location and car type.  

Item  Estimated cost 
Vacuum leak  $100-$200 
Replacing MAF  $300 
Cleaning MAF  $100 
Fuel pressure regulator  $200-$400 
Fuel pump  $1300-$1700 
Exhaust repair  $100-$200 
Air-fuel sensor/Oxygen sensor  $200-$300 

The bottom line 

  • The code indicates that Bank 2 has not sufficient air or has too much fuel. 
  • Though the code doesn’t pose a severe threat to a car, driving the car with this code for long periods can lead to internal engine damage.  
  • Do a fix and get the code rectified at the earliest to avoid damage to spark plugs, pistons, and catalytic converters. 
  • When diagnosing the P0175 code, it is crucial to complete the entire diagnostic process. Many people will immediately change the air-fuel sensor or oxygen sensor when they get a bad reading. However, the main reason could be a dirty or malfunctioning mass air-flow sensor or a vacuum leak, leading the O2 or MAF sensor to read differently to compensate. 

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