Definition of the code P0175
P0175 System too rich (Bank 2)
What does the P0175 code mean
P0175 indicates that the engine control module (ECM) is detecting too much fuel and not enough oxygen in the fuel/air ratio (AFR). This code is set when the ECM cannot compensate for the amount of air or fuel needed to bring the air/fuel ratio back to the set parameters.
For gasoline engines, the most efficient and economical air/fuel ratio is 14.7:1, or 14.7 parts air to 1 part fuel. This ratio also ensures maximum power during the combustion process.
The combustion process is very simple but delicate. In most vehicles, there are four to eight combustion chambers in the engine. Air, gasoline, and a spark strike the combustion chambers, creating an “explosion” (better known as combustion). The spark appears in each combustion chamber a nanosecond after the air and fuel hit the chamber to ignite it. There is a piston in each combustion chamber; each piston is pushed down by combustion at a rapid rate and at different heights.
The differential timing of each piston is determined by the air/fuel ratio and the engine timing. When the piston is lowered, it must return to the top position for regulation before the next combustion process. The piston is forced to slowly return to the top each time one of the other cylinders undergoes its own combustion process, since they are all connected to a rotating assembly called a crankshaft. It is almost like a juggling effect; at any given moment one piston is rising while another is on top, and yet another is falling.
If something in this process fails, the internal engine components will work harder and work against each other, or the engine may not run at all. In the case of code P0175, there is probably an increase in fuel consumption, because the ECM has detected that too much fuel is being consumed.
What causes a P0175 code?
- Fuel injector clogged, clogged or leaking.
- Defective fuel regulator
- Defective air sensor or dirty air mass
- Defective coolant temperature sensor
- Defective thermostat
- ECM needs to be reprogrammed
- Defective or dirty oxygen sensor
- Vacuum leak
- Fuel supply problem
- Incorrect fuel pressure
What are the symptoms of code P0175?
- Increased fuel consumption
- Soot or black deposit in the exhaust gas
- Engine light illumination
- Strong exhaust odors
How does a mechanic diagnose a P0175 code?
- Check fuel pressure
- Check fuel injectors for restrictions
- Checks the fuel injector pulse
- Checks the fuel lines for thickening or cracks.
- Inspects all vacuum lines for cracks and damage
- Checks oxygen sensors
- Uses scan tool to read engine temperature, then compares results with infrared thermometer
The most common errors when diagnosing code P0175
- Not checking engine temperature with scan tool and comparing it with thermometer
- Convincing that a component is defective without verifying it with testing.
How serious is code P0175?
- A system that runs too rich will force the catalytic converter to filter out more impurities, shortening its life.
- The resulting increase in fuel consumption can be very costly.
- An inadequate air/fuel ratio causes the engine to work harder, shortening its life span
- The engine will generate higher levels of harmful pollutants.
What fixes can repair a P0175 code?
- Replacement of broken or damaged vacuum lines
- Cleaning or replacing oxygen sensors
- Clean or replace air mass flow meter
- ECM Reprogramming
- Fuel Pump Replacement
- Fuel Filter Replacement
- Replacing a damaged or punctured fuel line
- Replacing a damaged fuel injector
- Replacing a clogged thermostat
- Replacement of a defective coolant temperature sensor
Additional notes on code P0175
I highly recommend checking that the vehicle’s cooling system is working properly. If the vehicle is running at an excessively low temperature, the engine will always run at a rich rate. This is because the ECM is designed to run at a rich rate when it is cold to help warm up the engine more quickly. If the coolant temperature sensor is faulty or the thermostat is open, the vehicle may never reach a warm temperature, causing it to always run at a rich rate.
