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Engine Brake Laws No. IA Local / posted

Iowa Engine & Jake Brake Rules

Iowa bans no engine brake statewide. The state law is the muffler statute (Iowa Code 321.436): a working muffler, no cutout or bypass. A 1999 bill to restrict engine brakes (SF 311) died, so the real rules are local. Counties like Buena Vista, Sac, and Pottawattamie and cities such as Iowa City pass ordinances and post signs; Buena Vista County sets a $250 civil penalty. Keep the engine brake on open grades where nothing is posted.

Ban scopeLocal / posted
Muffler lawYes (the legal hook)
Where postedLocal and common, heaviest in the northwest and along truck routes
FineLocal civil penalty; Buena Vista County sets $250
01 The rule

How Iowa handles engine braking

Iowa bans no engine brake statewide. The state law is the muffler statute (Iowa Code 321.436): a working muffler, no cutout or bypass. A 1999 bill to restrict engine brakes (SF 311) died, so the real rules are local. Counties like Buena Vista, Sac, and Pottawattamie and cities such as Iowa City pass ordinances and post signs; Buena Vista County sets a $250 civil penalty. Keep the engine brake on open grades where nothing is posted.

02 On the road

What to watch for

Iowa Engine Brake FAQ

Are engine brakes banned in Iowa?
Iowa has no statewide ban. The restriction is local and posted on "NO ENGINE BRAKE" signs. Iowa bans no engine brake statewide.
Where are the "NO ENGINE BRAKE" signs in Iowa?
Local and common, heaviest in the northwest and along truck routes. Buena Vista, Sac, and Pottawattamie counties and cities such as Iowa City pass engine-brake ordinances and post 'Engine Brake Ordinance Enforced' or 'Vehicle Noise Laws Enforced' signs. An Iowa DOT permit is required for signs on state highways.
What is the fine for using an engine brake where it is banned in Iowa?
Local civil penalty; Buena Vista County sets $250. Amounts vary by county and city, so confirm the local figure. The state muffler violation is a separate scheduled offense.

Reference information for planning, not legal advice. Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it. Last reviewed July 2026. Source: https://www.legis.iowa.gov/docs/code/321.436.pdf. See our Terms & Disclaimer.

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