Vermont CDL Permit Practice Test 2026 - Free CDL Permit Practice Questions and Study Guide

The purpose of the air intake heater in diesel engines is primarily to assist in starting the engine in cold weather. Diesel engines rely on the heat generated by compression for ignition, but in low temperatures, the air entering the engine can be too cold to ignite the diesel fuel effectively. The air intake heater warms up the incoming air, which helps achieve the necessary temperature for combustion, making it easier for the engine to start during chilly conditions.

This function is crucial because cold weather can lead to starting difficulties, increased wear on the engine components during prolonged cranking, and higher emissions due to unburnt fuel. Consequently, the air intake heater is specifically designed to mitigate these cold-start issues by ensuring a more favorable environment for combustion from the moment the ignition takes place.