Exhaust Pipe Smoke - Black

Easy to follow step by step repair guide on how to repair black smoke from an automotive engine exhaust system, these step are presented in order of popularity, this article pertains to most vehicles.

Difficulty Scale: 4 of 10

Begin with the vehicle on level ground, parking brake set while wearing protective eyewear and gloves.

Step 1 - If the check engine light has illuminated the PCM has detected a malfunction that could be causing the black smoke such as a shorted fuel injector. Visit - Read trouble codes

Check Engine Light

Step 2 - When a fuel pressure regulator fails it allows raw fuel to enter the engine producing black smoke. Visit - Check fuel pressure regulator

Inspecting Vacuum Feed Line

Step 3 - A stuck or shorted fuel injector can allow too much fuel to enter the engine. Visit - Fuel injector test

Testing Fuel Injector

Step 4 - Occasionally a computer can malfunction holding the injector drivers open longer than it should, causing an excess of fuel producing the black smoke.

Computer Module

Step 5 - A bad computer system ground can lead to a malfunction that can include allowing too much fuel to enter the engine producing black smoke, inspect wiring harness grounds at the battery and engine.

Computer Ground

Step 6 - On older engine's inspect under the hood for vacuum leaks which can cause the computer to malfunction creating black smoke. Visit - Checking vacuum leaks

Broken Vacuum Line


Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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