Would it be possible to make trucks with a kill switch to prevent them from being used for murder?

What would be the possible problems? I figure if we can make airbags deploy from a hit to the vehicle, why couldn’t we make engines freeze. Not permanent. You have to physically enter a four digit number in the engine to get it running again. The actual kill switch is somewhere deep in the engine where only a mechanic can reach.
What would be the flaws with such an idea?