Three questions about what actually broke will tell you which part to order. Most jobs turn out to be glass only once you look.

When your wing mirror is damaged after a clip or a scrape, the natural instinct is to replace the whole thing. In most cases that is overkill. The decision between glass only and a complete mirror assembly comes down to three questions about what actually broke. Here is how to read it.

The decision tree

Walk through these three checks in order. Stop at the first one that gives you a clear answer.

One. Does the housing rotate when you push it

Push the mirror housing forward then back with the heel of your hand. If it folds inwards on impact and springs back out by hand, the hinge mechanism is intact. You probably only need glass. If the housing wobbles or sits at the wrong angle and stays there, the inner hinge or the mounting arm is damaged. That needs a full unit.

Two. Does the motor still adjust the glass

Sit in the driver seat, use the in cabin adjustment to tilt the mirror up and down, left and right. A motor that hums but does not move the glass, or a motor that does nothing at all, is a unit replacement. The motors inside a complete mirror are not user serviceable.

Three. Is the housing paint damaged beyond cosmetic touch up

A scrape that took the paint off the cover plate is fixable with a replacement cover, which costs about twelve pounds primed for paint matching. A scrape that cracked the housing itself, where the cover meets the mounting arm, is a unit replacement.

Complete wing mirror unit ready for fitting
A complete mirror unit ships fully assembled with glass, housing, motor and indicator. Plug the loom in and you are done.

What a glass only replacement actually involves

If all three checks pointed at glass, the job is genuinely fifteen minutes. Stick on glass sticks over the top of the broken original. Clip on glass replaces the original with its own backing plate. Heated function carries over via two wires that are already in the housing. No tools beyond a plastic trim removal stick if you went clip on, nothing at all if you went stick on. Cost, eight to eighteen pounds for the part.

What a complete unit replacement involves

A complete unit is a bigger job, but it is still a home garage task on most vehicles. The mirror unbolts from the inside of the door, usually via a panel that pops off behind the door card upholstery. Underneath is a single multi pin connector and three or four bolts. Unplug the connector, undo the bolts, fit the new unit in reverse. Twenty to forty minutes depending on how cooperative the door card is. Cost, thirty to seventy pounds for the part.

The painted cover trap

If you are replacing a complete unit on a car with painted side mirrors, the new unit will ship primed black, not colour matched. Factor the painting cost in. A body shop will charge twenty five to forty pounds to colour match and respray a single cover. Or send the cover to a mobile SMART repair specialist, often half that.

When the answer is neither glass nor unit, it is just the cover

Sometimes the only damage is the cosmetic cover, the painted shell that clips over the front of the mirror housing. The glass, the motor, the heater and the indicator are all fine. The cover scrapes off in a low speed clip. Replacement covers are about twelve pounds. They unclip with a plastic trim tool in under five minutes. Worth a check before you commit to ordering anything bigger.

Buying tips for whichever route you pick

  • Always order the correct fitting side. Left passenger and right driver mirrors are not interchangeable on UK vehicles.
  • Match the spec exactly. Heated to heated, electric to electric, indicator to indicator. Mismatched units cause wiring loom issues at fitting time.
  • Check for two year warranty minimum on the part.
  • If you are buying a complete unit and your car has a power folding function, confirm the new unit includes it. The wiring loom changes between folding and non folding.

Most wing mirror jobs in UK family cars and vans turn out to be glass only once you actually look. Save the price difference and use it on a proper trim removal kit while you are ordering.