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P0175 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


This P0175 OBDII diagnostic code reports that an oxygen sensor located in bank 2 has detected a very high condition or there is insufficient oxygen in the exhaust gases. On 6-, 8- and 10-cylinder engines, bank 2 corresponds to the side of the engine that has cylinder number 1.

It should be noted that this DTC code is very similar to P0172, and it is very likely that your vehicle will display both codes at the same time. Generally speaking, the gasoline mix that the PCM computer sends out is very high.


P0175 indicates that the Engine Control Module (ECM) detects too much fuel and a lack of oxygen in the air/fuel ratio (AFR). This code will be set when the ECM cannot compensate for the amount of air or fuel required to bring the air-fuel ratio back to set parameters.

For gasoline engines, the most efficient and economical fuel-to-air ratio is 14.7: 1, or 14.7 parts air to 1 part fuel. This ratio also creates the maximum amount of energy during the combustion process.

The combustion process is very simple but fragile. In most vehicles, there are four to eight combustion chambers within the engine. Air, gasoline, and sparks are delivered to the combustion chambers to create an “explosion” (better known as combustion). The spark is sent to each combustion chamber one nanosecond after air and fuel reach the chamber to ignite it. There is a piston in each combustion chamber; Each piston is forced down by combustion at a rapid rate and at different times.

The difference in the timing of each piston is determined by the air-fuel ratio and engine timing. Once the piston is down, it should return to the top position in time for its next combustion process. The piston is forced back little by little each time one of the other cylinders undergoes its combustion process, as they are all connected to a rotating assembly known as a crankshaft. It’s almost like a juggling effect; At any given moment, one piston is on its way up, while another is at its peak, and another piston is on its way down.

If something in this process goes out of sequence, the internal components of the engine will work harder and work against each other, or the engine may not run at all. In the case of the P0175 code, there is likely increased gas consumption as the ECM has detected that too much fuel is being used.


  • A clogged, stuck, or leaking fuel injector
  • Faulty fuel regulator
  • Dirty or faulty mass airflow sensor
  • Faulty coolant temperature sensor
  • Faulty thermostat
  • ECM needs reprogramming
  • Dirty or faulty oxygen sensor
  • Vacuum leak
  • Fuel delivery problem
  • Incorrect fuel pressure


  • Increased fuel consumption
  • Soot or black residue from exhaust
  • Check engine light illumination
  • Strong exhaust odors


  • Check the fuel pressure
  • Inspects fuel injectors for restrictions
  • Checks the fuel injector pulse
  • Examine fuel lines for pinches or cracks
  • Inspects all vacuum lines for cracks and deterioration
  • Inspect the oxygen sensors
  • Use a scan tool to read the engine temperature, then compare the results with an infrared thermometer.

Common mistakes

  • You don’t check the engine temperature with a scan tool and compare it to a thermometer
  • Consider a bad component without verifying by testing

How serious is this?

A system that is running too rich will force the catalytic converter to filter out more contaminants, shortening the life of the catalytic converter. The resulting increase in gas consumption could be very costly. Improper air-fuel ratio makes the engine work harder, which will shorten the life of the engine. The engine will create higher levels of harmful contaminants.

What repairs can fix the code?

  • Replacement of cracked or broken vacuum lines
  • Cleaning or replacing oxygen sensors
  • Cleaning or replacing the mass airflow sensor
  • Reprogramming the ECM
  • Replace the fuel pump
  • Replacing the fuel filter
  • Replace a damaged or pinched fuel line
  • Replace a faulty fuel injector
  • Replace a stuck thermostat
  • Replace a faulty coolant temperature sensor

Related codes

None listed.


I highly recommend checking that the vehicle’s cooling system is working properly. If the vehicle runs abnormally cold, the engine will always run-in good condition. This is because the ECM is designed to run at a high speed when cold to help warm up the engine faster. If the coolant temperature sensor is faulty or the thermostat is stuck, the vehicle may never reach a warm temperature, which will always keep it running in good condition.