Tema 21: maintenance, breakdowns and the engine in the DGT exam

The engine cannot sound or pollute above the limit, and a breakdown blocking the carriageway must be signalled and cleared as soon as possible.

Reviewed on 6 October 2026 · sources: BOE and DGT

This tema asks what the rules require of the engine and mechanical parts, and what to do if a breakdown blocks the carriageway.

A vehicle may not be driven if it emits noise or exhaust fumes above the regulatory limits. A police officer (agente) may immobilise one that exceeds them.
A vehicle's mechanical parts must not pose any danger to its occupants or to other road users.
The engine and fuel system must be designed to avoid fire or explosion risks.
If an accident or breakdown leaves the vehicle or its load blocking the carriageway (calzada), you must signal it and clear it as soon as possible.
Whenever feasible, move it off the carriageway and position it as if you were parking.

Watch out: driving with a free exhaust, without the required silencer, is banned.

Source: RGC arts. 7, 130; RGV art. 11 (points 9 and 10).

Key rules of topic 21

A vehicle may not be driven if it emits noise or exhaust fumes above the regulatory limits.

A vehicle's mechanical parts must not pose any danger to its occupants or to other road users.

If an accident or breakdown leaves the vehicle or its load blocking the carriageway, you must signal it and clear it as soon as possible.

Whenever feasible, move it off the carriageway and position it as if you were parking.

Study topic 21 step by step: the rule, its citation and exam-style questions.