7e8 Engine Code Chevy [Causes, Symptoms & Fixes]

When your fuel or air intake systems fail, it simply means that the 7e8 Engine code for your Chevy vehicle is activated. And this could be the reason for your low fuel mileage or poor engine performance.

However, in this situation, a proper automobile diagnosis is required to establish the root cause of the 7e8 Engine code and resolve it as quickly as possible.

Although this code will not prevent your automobile from driving, it is critical for you to resolve it as soon as possible in order to experience improved comfort and gas mileage.

In this post, we will help you understand better the meaning of the 7e8 engine code on your chevy, the several symptoms, causes, and how to resolve it.

7e8 Engine Code Chevy

What Does The Chevy Engine Code 7e8 Mean?

7e8 engine code represents the engine data stream of the vehicle which indicates air pressure loss for the evaporative emission control system. It’s a generic engine code that indicates there’s a problem with the vehicle’s emission system.

It simply signifies that the car is experiencing fuel or air intake problems. Also, it causes the check engine light to illuminate on the dashboard.

Symptoms of 7e8 Engine Code 

1. Check Engine Light Comes On

The most noticeable warning light on the dashboard is the Check Engine Light. It is the most misinterpreted indication a car delivers concerning a suspected engine problem because it has different meanings.

This is why you should check the stored code to determine the severity of the problem and how urgently the patch is required to save the engine.

2. Darker Exhaust Smoke 

This problem is also connected to the air-fuel ratio. When there is inadequate air in the combustion chamber, additional fuel is injected, which will result in fuel not completely being burned.

Unburned or inefficiently burned fuel results in darker-than-normal exhaust smoke.

3. Poor Fuel Efficiency 

The vehicle’s fuel efficiency suffers as a result of the inadequate air-fuel ratio. You will go to the petrol station more frequently than usual.

4. Decreased Engine Performance

Another sign of the 7e8 engine code is decreased engine performance. You will notice a reduction in engine power as the automobile struggles to climb under load.

This is due to an incorrect air-fuel ratio in the combustion cylinder. It can be overly rich or underweight.

Also, if the engine does not receive enough air to complete the combustion of the fuel, it may consume more gas than intended. As a result, the smoke from the exhaust will shift, sometimes being darker than typical.

5. Revving Noise When Your Car is Idling 

Chevy owners who have given their vehicles an OBD II 7E8 code report hearing their vehicles revving while still in idling mode. Unusual engine sound or noise might potentially be a sign of a 7E8 problem.

Causes of 7e8 Engine Code in Your Chevy

1. Broken Fuel Filler Cap 

The fuel filler cap is critical to the vehicle’s evaporative emission system. It keeps fuel from evaporating in the gas tank and keeps water and other particles from entering the tank and contaminating the fuel.

This filler cap also includes a valve that regulates the pressure within the fuel tank.

A gasoline smell in the cabin, failure to tighten correctly, and the check engine light turning on are all signs of a failed or broken fuel filler cap. 

A defective one lets gasoline evaporate or fails to control air pressure within the fuel tank. Because of the imbalance caused by the evaporative emission system, these situations might result in the 7e8 engine code. 

2. Leaking or Damaged Pipes

Fuel vapor lines are pipes that return surplus fuel to the gas tank for recirculation. They primarily transport fuel vapor from the fuel pump to the gas tank, where it cools and condenses into liquid gasoline.

Therefore,  if the gasoline vapor lines leak, or get disconnected, it will lead to severe fuel loss. The engine may be deprived of gasoline, resulting in the 7e8 engine code. 

3. Faulty Pressure/Purge Control Solenoid Valve

Your car’s emissions are principally regulated by the Purge Control Solenoid Valve. When the engine is turned off, it is regulated by a computer program to prevent unburned fuel vapors from leaking into the atmosphere. 

Before being permitted to flow back into the engine, the caught gasoline vapors are momentarily kept in the charcoal canister. Purge Control Failure The system identifies a problem when the solenoid valve does not respond to control signals. 

The 7e8 engine code is then activated by the control module to warn the driver of the problem.

4. Faulty Canister Close Valve 

Another important part of the vehicle’s pollution control system is the fuel canister. It is loaded with charcoal to capture fuel vapor that would otherwise escape into the atmosphere. 

The trapped gasoline vapor is burned as it returns to the engine through the purge valve, also known as the canister close valve. That is how fuel canisters reduce pollutants in the atmosphere.

A malfunctioning fuel canister does not accomplish its job properly. The issue will be identified and reported as 7e8 engine code. 

5. A Faulty Fuel Pump Seal

The fuel pump seal, often known as a gasket, prevents fuel oil from leaking onto the cam case. In other terms, it seals up the fuel pump. If this is not the case, fuel leaks will cause issues that may result in the engine running out of fuel. This may also result in the 7e8 code in your chevy.

How to Fix a 7e8 Engine Code in a Chevy

Fixing this error code entails determining the underlying reason and taking relevant action. It may be necessary to replace or repair the previously listed malfunctioning EVAP control system components.

  1. If the fuel filler pipe is broken, consider replacing it.
  2. The malfunctioning canister closing valve should be replaced. At the same time, check to see if the purge control solenoid valve is damaged. It can be fixed or replaced.
  3. Replace any cracked fuel pump seals.
  4. Repair or replace any leaking or disconnected vapour lines, depending on the severity of the damage.
  5. If the gasoline tank cap is incorrect, determine whether it is simply a question of improper tightening or if the cap is broken. If the cap is damaged or missing, you must replace it.
  6. If the tank pressure sensor fails, replace it.


How Do I Diagnose 7e8 Engine Code For Chevy?

You can easily diagnose the 7e8 engine code for chevy with an OBD2 scanner. This tool will enable you to interpret the code and identify likely reasons or problems to be rectified. Therefore,  If you have the proper scanning tool, this process is simple.

Also, a visual check for fuel system leaks or sniffing the cabin for gasoline odours can be part of the diagnosis. However, if you are not experienced with automobiles, we recommend you send your car to a professional for a proper diagnosis.

Are the Engine Codes 7e8 and 7e9 the Same?

No. The two error codes are related but never identical. The engine powertrain is represented by the 7e8 code, whereas the transmission powertrain is represented by the 7e9 code. Both are not life-threatening, but they should be handled as quickly as possible.

Read: Transmission Control System MIL Request


The 7e8 Engine Code denotes the powertrain of an engine and should be distinct from the 7e9 code, which denotes the powertrain of a transmission. A variety of causes can contribute to the 7e8 engine code Chevy. That is why a good diagnosis is critical before attempting to solve the problem. Therefore, if you have a multi-purpose OBD2 scanner, you can diagnose the situation at home. Some OBD2 gadgets will even propose solutions that you may do in your garage.