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$7e8 Engine Code: A Detailed Overview

March 20, 2024 | Victor Lukasso

The $7e8 engine code is among the complex error codes that might be shown on your OBD-II scanner.

The $7e8 engine code is often accompanied by the $7e9 error code, which both signify an issue in the engine data stream.

A $7e8 error code signifies air pressure loss for the emission control system which can also be likened to an issue with the engine power train. The $7e9 code indicates a problem with the engine transmission.

This article will extensively discuss the $7e8 engine code, including its meaning, causes, and fix.


What is Engine Code $7e8

Error code $7e8 is a diagnostic trouble code that indicates air or fuel intake into the engine control system, thereby leading to a loss of air pressure in your vehicle’s evaporative emission control system.

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The engine generates its power from the internal combustion cycle in the cylinder, and the combustion chamber uses petrol mixtures and trapped air to create heat and produce a spark which in turn moves the car.

Depending on the model of your cylinder head, uncompressed air or unburnt fuel can get into the control system and reduce air pressure.

Some car models, such as the Chevy and GMC Sierra, will also show this code if the knock sensor detects a vibration from the engine.

This error code is a minor issue and may not cause any problems because it’s often resolved in minutes, and a lousy sensor might be responsible for showing the code.

If you doubt the cause of the error code, you can employ a multiple-purpose OBD-II scanner for this purpose.

It’ll reveal the reason(s) why your check engine light is turned on and provide possible fixes for you.

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$7e8 Engine Code – Causes

Here are possible reasons why the $7e8 error code will be displayed on your check engine light.

  • Leaking fuel vapor lines
  • Disconnected vapor lines
  • Damaged Canister
  • Bad Canister Close Valve
  • Bad fuel tank pressure valve
  • Unplugged fuel vapor line
  • Faulty pressure control solenoid valve
  • Bad fuel pump seal
  • A Bad fuel filler pipe
  • Bad fuel filler cap

That’s it for the causes of the $7e8 engine code Chevy.

How to Fix the $7e8 Engine Code

The $7e8 error code revolves around the air and fuel mixture entering the engine control system.

Here are some DIY tips you can implement to fix the error code.

  • Get a fuel cap replacement
  • Run an EVAP leakage test on your car
  • Perform a smoke test on your EVAP system
  • Check if your fuel level is between 15% – 80%
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You can now clear the codes on your OBD-II scanner and perform a new test. The codes should clear off by now.

Also, endeavor to perform an EVAP test on your car after driving for 10,000 to prevent poor gas mileage and the $7e8 engine code.

You can take your car to a professional mechanic if the engine code persists after initiating any of the above fixes.

$7e8 and $7e9 Engine Code

Even though the two engine codes seem to relate to the engine control module, they differ.

The $7e8 engine code indicates a problem with the engine powertrain; meanwhile, the $7e9 suggests a problem with the transmission powertrain.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.