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Engine exhaust is black

Engine exhaust is black

Stihl · RZ Zero-Turn Mowers

What does Engine exhaust is black mean?

The engine is producing black smoke from the exhaust. This usually means the engine is not getting enough air or the fuel mixture is too rich.

Common Causes

  • Dirty air filter
  • Engine choke control is in closed position (Carbureted Models)

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Replace the air filter. Refer to the engine operator's manual.

  2. 2

    If applicable, move the choke control to the open position.

Browse all codes in this manual (9)
Verified technical data. Last updated: April 2026

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Source: Stihl RZ Zero-Turn Mowers
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