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451 ED Heater Fault

Mod Details
PremiumYes Difficulty Mod ID1651 Creditevilution For451 Fortwo Link Copy to Clipboard

A new common problem started appearing quite regularly on 451 Electric Drive Fortwos, the heater stopped heating.

Sometimes it’ll work for a while and stop working again. The issue here is that when you own an electric smart, if you want to use the heater, you must really need it because we generally don’t use it as it affects the range too much. So, less than ideal if you’re freezing your nuts off (or female equivalent).

How Can A Heater Not Work?

In petrol and diesel powered cars, the coolant is pumped around the engine and then into a radiator in the cabin. Air is blown over this radiator and into the car. On the electric drive version, the “engine” doesn’t create enough heat to warm the coolant enough to heat the cabin. So instead it has an electric heater.

This electric heater takes power from the 400 volt drive battery, not the 12 volt accessory battery. As you can imagine, a 400 volt heater can get very hot, very quickly.

However, you aren’t controlling 400 volts with the heater controller on the dashboard so the heater pack has to have some sort of control circuitry built in. Circuitry that measures voltages, heat, setting input etc. All of that is used to stop things possibly bursting into flames I guess.

The problem is that it only takes 1 thing to go wrong and it puts the heater into safe mode. By that I mean it does bugger all.

Smart Say Replace The Heater

I’m a strong believer in asking smart for the price of a part because if it’s cheap, don’t waste your time repairing. That’s when I found out the replacement 400 volt PTC heater is nearly £1400. No fucking way I’m paying that. Smart can poke it in their hole.

Fixing The Old Heater Accidentally

There’s nothing quite like fixing a fault in 60 seconds for free without even trying.

The Fix


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