Heated Rear Window Not Working? Causes and Fixes

On a frosty morning, a working heated rear window is the difference between setting off and standing there scraping. If yours has stopped clearing, or only clears in patches, here is what might be going on. If the glass itself has shattered, our heated rear window replacement page explains how we fit a new one.

How a Heated Rear Window Works

The thin lines across your rear screen are a heating element printed onto the glass. Power flows in through a connector on one side, along the lines and out the other side, warming the glass enough to clear mist and frost. A fuse and relay control the circuit, and many cars switch it off automatically after a few minutes.

Common Reasons It Stops Working

A blown fuse or a faulty relay

If none of the lines warm up at all, start with the fuse. Your handbook will show which one protects the rear demister. A faulty relay or switch gives the same symptoms.

A loose or broken connector

The electrical tabs are bonded to the glass at each side of the screen. They can work loose over time, especially on tailgates that open and close many times a day. If the fuse is fine, this is the next thing to look at. The tabs are part of the glass, so once one has come away, the fix is a new heated rear window.

Scratched or broken heating lines

If most of the screen clears but some strips stay misted, individual lines are probably broken. Luggage, bike racks and scraping the inside of the glass are the usual culprits. The lines are printed onto the glass, so broken ones also mean a new screen.

Cracked or smashed glass

A damaged rear screen cannot be repaired. It needs replacing, and the new glass comes with a new heating element built in.

When You Need a New Heated Rear Window

• The glass is cracked, chipped or smashed.
• Heating lines have broken, leaving strips of the screen misted.
• A connector tab has come away from the glass.

What Happens When We Replace It

We vacuum any broken glass out of the boot and cabin, remove the trims and wiper, and fit a new heated rear window made for your car, clear or privacy tinted to match. We reconnect the heating and any aerial built into the glass, then test the demister before we leave. Allow about two hours, because clearing the broken glass out of the car is part of the job, and leave the car for about an hour afterwards before you drive it.

Until It Is Fixed

The Highway Code says you must be able to see out of every window before you drive, so clear the rear screen fully before setting off. If the glass is broken, avoid driving with loose glass in the car and call us on 07426 801611 so we can get it sorted quickly.