Mod Description

How to change the glow plugs in your smart fortwo.

Mod Details

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When Do The Glow Plugs Need Changing?

So far, I haven’t seen any official schedule for changing the glow plugs on the smart. It would seem that smart expect you to change the glow plugs when the error light comes on to tell you that there’s a fault.

What normally happens is, when you turn the key to position 1, the glow plug light comes on and a few seconds later it goes out. The light going out and staying out tells you that the glow plugs are OK. If, after the engine has been started, the glow plug light comes back on, you have an error.

The glow plug light should eventually go out again after a while.

So, the duration at which you change them is up to you. Personally, I’d recommend you change them every 4th service instead of waiting for one to fail. The reason is simple. It’s not unknown for glow plugs to work for more than 100,000 miles, however, at that sort of age, you are going to have a nightmare getting them out. It’s far better to change them twice as often and for it to be a 20 minute job each time rather than having to deal with seized or snapped glow plugs.

OBD Error Codes

As is the case, there are those of you out there who can’t survive without your fault code readers.

P0380
P0381
U0106
U0307
U0407
P1481 (smart specific error code)

Glow Plug Removal – Theory

Open the engine cover to reveal your oil burning engine. At the back of the name plate are 3 cutouts. Directly below these is where the glow plugs are located.

The diesel engine in a 451 and 450 are the same but a few things are packaged differently around it. These pictures were taken of a 451 which has slightly easier access as the rubber conduit can be easily pushed out of the way.

Looking down the back of the name plate behind the indents you’ll see the glow plug connectors. This is plug 3, it the furthest left of the 3 plugs.

Here is plug 2 in the centre.

And finally, this is plug 1. They are labeled from right to left like the cylinders.

The connectors on the top pull off. They can be quite stiff but hooking something behind them helps. Some glow plugs have a threaded connector, however, the smart’s glow plug connections are smooth. Below is a brand new glow plug. Generally they are less than £10 each.

With the electrical connection removed you should see the hexagon head. You’ll need a long 10mm socket.