Home TroubleshootingOBD Codes P0172 Chevy: Meaning, Causes And Symptoms

P0172 Chevy: Meaning, Causes And Symptoms

by Kelvin Yates

The Chevy brand of vehicles is known for its use of quality and advanced technologies. The fuel consumption on their engines is relatively low, meaning you won’t spend much on fuel. However, their Chevy vehicles have a common problem which is the P0172 Chevy code.

The P0172 Chevy code is a Diagnostic Trouble Code (DTC) that your vehicle’s engine combustion unit system displays when there’s too much fuel or too little oxygen in the fuel combustion chamber. To see the P0172 code, you have to connect the diagnostic link connector to the OBD II scanner.

The combustion in the engine is a reaction between fuel and oxygen (air). If there isn’t enough fuel going to the engine or the air intake system doesn’t allow enough air into the combustion chamber, the engine will not be able to produce enough energy. The engine control unit maintains balance in the engine. It ensures that the air-fuel ratio stays within limits. If there’s an excess of fuel in the engine, the ECU will send the P0172 code.

P0172 Code

The P0172 code from the oxygen sensor is a signal that the air-fuel mixture in the engine has too much fuel or little oxygen. The oxygen sensor monitors the exhaust from your car’s engine and tells the car’s computer whether or not it’s safe to burn fuel.

If there isn’t enough oxygen in the exhaust to support combustion, then the engine will run rich and produce excess emissions. The oxygen sensor doesn’t detect fuel, just oxygen. If there’s unburned fuel in the engine that raises the fuel ratio in the mixture, the oxygen sensor will interpret it as oxygen shortage.

The ECM uses this information to calculate an appropriate air/fuel ratio for your car. This ratio is calculated based on how much oxygen is present in the exhaust stream and how much fuel has been injected into the cylinders. If the ECU throws the P0172 code, it has been detected that the air-fuel ratio is less than stoichiometric (14.7:1).

P0172 System Too Rich Bank 1

The P0172 Chevy code can be caused by a leaking fuel injector in the engine’s intake side. Excess fuel will go into the cylinders altering the air-fuel mixture. The oxygen sensor detects the rich condition in the cylinder, and the ECU sends the P0172 code.

The P0172 code is a generic OBD-II trouble code and is not associated with any specific problem. Technically, the p0172 code is associated with a fault in the MAF sensor (Mass Air Flow Sensor), which measures the amount of air entering the engine. However, there are other causes of the P0172 code.

P0172 Chevy Symptoms

A common symptom of the P0172 chevy code is engine misfiring, but that only helps if you pay attention to the sound from your car engine. A more visible sign is the check engine light from your car’s computer that comes on when there’s a fault in the engine. The symptoms are similar to those of an engine-rich condition.

  • Low power when accelerating.
  • Misfiring.
  • Strong fuel smell from the exhaust.
  • High fuel consumption.
  • Fouled spark plug.
  • Hesitating engine.
  • Rough idling.

P0172 Chevy

P0172 Chevy Equinox

The Equinox is a model from Chevrolet and has amazing features like adaptive cruise control. The average repair cost is relatively lower than the ownership cost. However, some users complain that the Chevy Equinox frequently shows the check engine light associated with the P0172 Chevy Equinox.

The P0172 Chevy equinox code is a DTC code the engine control unit throws when the air-fuel mixture in the cylinder is too rich. A rich engine condition means there’s too much fuel in the cylinders and little oxygen. It is the opposite of a lean condition, which signifies a lack of fuel in the cylinders.

If your Chevy Equinox throws the P0172 code, there’s too much fuel in the cylinders. If the rich condition is in cylinder 1, the scanning tool will display “Bank 1”. The oxygen sensor does not detect how much fuel is in the cylinder, the oxygen. If there’s an excess of fuel in the engine, the sensor signals the ECU that there’s little oxygen for combustion.

P0172 Chevy Silverado

The name Chevy Silverado is known for its strong engine lineup. Although it’s a truck, it has a car-like interior with superior quality. Chevy Silverado trucks often get the P0172 code. The P0172 code is a number code the OBD-II scanner reads when you plug in the car’s diagnostic link connector.

The P0172 Chevy Silverado code is a generic OBD-II trouble code sent by the ECU when it detects that the engine is not getting enough air to support combustion. Causes of the p0172 Code in Chevy Silverado are outdated PCM software, faulty fuel injector, etc.

P0172 Chevy Impala

The Chevy Impala car is another vehicle from Chevrolet with impressive V-6 engine power. Its entertainment system connects with Apple and Android devices, giving users a lovely time on the road. However, the car is commonly affected by the P0172 code.

P0172 And P0175

The codes P0172 and P0175 are DTC codes the scanning tool reads when there’s a rich engine condition in your car. The P0172 code from the ECU indicates a rich system in “Bank 1”. The p0175 code indicates a rich system in “Bank 2” in the car engine.

Engine “Bank 1: is the side of the engine chamber where there is cylinder 1. Engine “Bank 2” is the side opposite “Bank 1”. If the ECU throws the P0172 code, there’s a rich condition in cylinder 1. If it throws the P0175 code, there’s a rich condition in “Bank 2”, opposite cylinder 1.

The upstream oxygen sensor positioned on the exhaust manifold of your car engine triggers the P0172 and p0175 codes. These sensors measure the amount of oxygen in the exhaust to determine how much it remains in the cylinders for complete combustion. If there’s too much fuel and not enough oxygen to burn it, the oxygen sensor throws a code. If cylinder 1 is oxygen-deficient, the scanner reads P0172 System Too Rich (Bank 1).

The upstream sensor sends voltage signals to the ECU. A prolonged high voltage reading means a rich condition; a low voltage reading means a lean condition in the engine. The ECU can throw both P0172 and PO175 codes simultaneously depending on the cause of the ich condition. P0172 and PO175 codes indicate a fault in the fuel injection system or the MAF. Further diagnosis will reveal the exact part that is faulty.

Car Engine Running Rich

A rich condition occurs when the engine’s fuel mixture is too rich, meaning there is more fuel than needed for proper combustion. The engine runs rich if it is not burning all of its fuel or there is little oxygen in the cylinders. The result is that there’s too much fuel in the exhaust gas.

It can cause various problems, but the most common one is a buildup of carbon deposits on the spark plug. If left unchecked, the rich engine can be dangerous for you and your passengers. When an engine runs rich, it produces higher carbon monoxide and unburned hydrocarbons. Both are toxic gasses that can cause sickness or even death if inhaled in large quantities over time. A rich engine condition is dangerous and should not be left unchecked.

System Too Rich Bank 1

If the ECU code signals that “Bank 1” is too rich, there’s excess fuel on cylinder 1 in the engine compartment. There’s an oxygen sensor on the side of the number one cylinder that checks the quantity of oxygen gas. Once it detects oxygen shortage, it shoots the P0172 chevy trouble code.

For the engine to generate enough power, the air-fuel mixture in the engine should be at the correct level, which for most gasoline engines is 14.7:1. This is the lowest emission point of the engine. The combustion in the engine will produce maximum power with the least amount of fuel. Excess fuel in cylinder 1 translates to inefficient combustion of fuel.

System Too Rich Bank 2

The rich bank two is associated with the P0175 code in the ECU. It means that there’s a too rich condition in bank 2, that is, there’s too much fuel and not enough oxygen in the cylinder opposite bank 1. A common cause of a too-rich bank 2 code is a leaking fuel injector.

A mix of fuel and air is needed to burn properly in the combustion chamber of a gasoline engine. The mixture must be just right, or the engine will run rough, misfire, and eventually stop running altogether.

Running Rich, Negative Long Term Fuel Trim

When your car engine is running rich, the fuel trim will read negative on the scanning tool, signaling the ECU to reduce the injector pulse. Fuel trim values range between negative 10 percent to positive 10 percent. Negative fuel trim shows that the PCM has detected a lean condition (lack of fuel). 

Fuel trim is a measure of the difference between the amount of air coming into the engine and the amount of fuel being injected into the cylinders. It can be expressed as a percentage or a number. This measurement aims to ensure that the engine is operating as efficiently as possible. In a closed-loop, the ECM/PCM uses the oxygen sensor input as a factor in conducting continual Fuel Trim changes.

Negative long-term trim is usually caused by high fuel pressure, leaking fuel injectors, or malfunctioning MAF sensors. If left unchecked, it can cause damage to your engine. Under normal conditions, the fuel trim reads zero.

P0172 Chevy

Car Running Rich Symptoms

The symptoms of a car running rich can be thick smoke from the exhaust pipe or a rotten egg smell from the exhaust. However, rich engine condition signs are similar to other car faults like oil leakage. If you suspect the engine is too rich, check for other symptoms before anything else.

Symptoms of the rich condition are:

  • Poor fuel management
  • Rotten egg smell from the exhaust
  • Check engine light
  • Thick black smoke from the exhaust
  • Dirty spark plug
  • High carbon monoxide content

Car Running Rich No Codes

Your car may show some signs of an engine running rich, like smoking, but it doesn’t display the DTC trouble codes. You should first confirm that the engine is running rich and the symptoms aren’t pointing to another fault, and then check for codes using a scanning tool.

To check for codes, hook up an OBD-II scanner to your car and see if the ECU throws any codes. If there aren’t any codes, this could point toward an issue with the oxygen sensor or the ECU.

The oxygen sensor regulates the amount of oxygen that enters the engine. When there’s a rich condition, the oxygen sensor throws the P0172 code, which the ECU interprets. Sometimes, the oxygen sensor can go bad and not throw codes even in a rich condition. If you suspect that your car engine is running rich, take the vehicle to a mechanic for diagnosis and repair. The ECU can also malfunction and fail to process the sensors’ input. If this happens, it will not throw codes.

What Causes A Car To Run Rich And Display P0172 Chevy

The most common cause of a running rich condition is a dirty air filter. When the air filter becomes clogged with dirt and dust, it restricts airflow into the engine. The mixture of fuel and air in the cylinders becomes richer (more fuel than air). There are other causes of the rich condition of cars.

1. Faulty MAF That Prompts P0172 Chevy To Appear

The mass airflow sensor is part of the engine’s fuel injection system. It regulates the amount of air that gets into the car engine. If it’s faulty, it will mismeasure air and inject too much fuel into the engine, causing a rich condition in the cylinder.

2. Oxygen Sensors Malfunction

The oxygen sensor in the exhaust manifold checks the amount of unburned oxygen in the exhaust. It tells the car’s computer how much fuel should be injected into the cylinder based on the amount of oxygen it detects. If the sensor mismeasures oxygen, it’ll send the wrong signal, and ECU injects too much fuel into the engine, causing a rich condition.

3. Faulty Fuel Pressure Regulator

If the fuel pressure regulator is stuck open, it can cause a rich condition in the engine because the fuel injector will send in excess fuel into the cylinder. The fuel injector works by pressure. It takes signals from the pressure regulator. When the pressure regulator is open, pressure builds up, and the injector sends in more fuel.

4. Faulty Fuel Injectors That Cause P0172 Chevy

A faulty fuel injector sends excess fuel into the cylinder, causing a rich condition. The fuel injector releases fuel when the pressure regulator sends a signal of pressure buildup. If it malfunctions, it’ll inject fuel even when there’s no need for it.

5. Damaged Engine Control Unit

The ECU is the car’s computer. If it malfunctions and misinterprets data, it can send excess fuel or less oxygen into the cylinders.

6. Damaged Coolant Temperature Sensor

The coolant temperature sensor alerts the ECU when there’s a temperature rise in the engine. The ECU will inject more fuel into the cylinders to balance the temperature rise, causing a rich condition in the engine.

Frequently Asked Questions On P0172 Chevy Code

What Does Running Rich Mean

If a car engine is running rich, too much fuel gets into the cylinder, causing an unbalanced air-fuel ratio. When too much fuel is in the cylinder, the oxygen sensor will detect it as low oxygen. There will be incomplete combustion of fuel, causing the engine to underperform. A car engine under ideal conditions should have low emissions. If any of the cylinders is running rich, it will cause the engine to misfire. When an engine is running rich, an excessive amount of unburned fuel can accumulate in the exhaust system. It puts the car in an unsafe operating condition. If left unchecked, the rich state results in expensive repairs and even engine failure. Fixing a running rich problem usually involves replacing faulty parts and cleaning up dirty throttle plates.

P0172 Code How To Fix

To fix the P0172 code, you begin by identifying the cause and seeking its solution. Most times, you will have to replace the faulty part, which can be the fuel injector. If a clogged component causes the P0172 code, you’ll isolate that part and clean or unclog it. OBD-II trouble codes like the P0172 code can have different diagnoses depending on the car type or model. To fix the P0172 code on the Chevy, take the vehicle to a mechanic for diagnosis and fix accordingly.

How Do You Diagnose The P0172 Code

Diagnosing the P0172 code is the job of the mechanic. To diagnose the p0172 chevy code, the mechanic will do a fuel pressure test, use noid lights to check the fuel injector pulse, check for vacuum leaks, examine the MAF and oxygen sensor, and check the air filter.

What Part Do I Need For A Code P0172

After diagnosing the cause of the P0172 trouble code, you may have to replace the faulty parts like the fuel injector, which is a common culprit. Any other part of the fuel or air intake system can cause the P0172 code. After diagnosis, you’ll purchase the faulty part and replace it. Parts you may have to replace if your Chevy vehicle has the P0172 Code are the fuel injector, spark plugs, fuel pump, air filter, thermostat, fuel regulator, and coolant temperature sensor.

Why Is My Car Running Rich

If your car engine is running rich, there’s too much fuel in the engine cylinders and less oxygen. When this happens, fuel will not burn properly, and the engine will produce less power than it should if the air-fuel ratio is stable. A faulty MAF sensor is a common cause of the rich condition in engines. If you have a car running rich, it means that the air-fuel ratio of your engine is not correct. The ratio should be 14 parts of air to 1 part of fuel. This ratio is called the stoichiometric ratio, and it is the ideal ratio for an engine to burn fuel efficiently and produce maximum power. A car running rich will usually have black smoke coming from the exhaust. Smoking is caused by unburned gas entering the combustion process; it leaves through the tailpipe. It also causes increased fuel consumption.

Can Dirty Fuel Injectors Cause The Check Engine Light

Dirty fuel injectors can cause the check engine light to come on. The fuel injector is responsible for spraying gas into your engine. If your car is not getting enough fuel or your fuel injector is clogged, it will be difficult for your engine to start up and run properly and the light comes on. Dirty or clogged jets on older cars with carburetors can cause the same symptoms as failing fuel injectors. The lack of an electronic control system on older models means that there is no way to diagnose failing fuel injectors without removing them and inspecting them manually. Newer cars use an electronic control unit (ECU) that monitors fuel pressure and flow through each injector; if one fails and begins leaking, it will register as a fault within minutes.

Conclusion On P0172 Chevy

The P0172 Chevy code is a diagnostic trouble code in your vehicle. This Diagnostic Trouble Code (DTC) is set when the ECU or PCM detects a problem in the engine. Symptoms of the P0172 Code include high fuel consumption, poor engine performance, and smoking. To fix the P0172 code, make a proper diagnosis to ascertain the cause and proceed to replace the faulty parts.


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