Symptoms
- Mirror stays frosted or foggy while the rest of the car's heated features work
- Other heated features (like a heated rear window) may work fine
- No visible warmth felt on the mirror glass when the feature is on
- One mirror affected while the other heats normally
Likely causes
- CommonFailed heating element in the mirror glassThe thin heating grid embedded in or behind the glass can fail with age, similar to a rear defroster.
- CommonBlown fuse for the heated mirror circuitA shared fuse can affect one or both mirrors depending on wiring.
- PossibleDamaged wiring or connector at the mirrorThe flexible wiring through the door and mirror base can fray over time.
- Less commonFaulty relay or switch for the heated mirror featureSome vehicles use a shared switch or relay for heated mirrors and rear defrost.
What to do
- Confirm the heated mirror feature is actually turned on, since some vehicles link it to the rear defroster button rather than a separate switch.
- Check the relevant fuse for heated mirrors or rear defrost, since they sometimes share a circuit.
- Feel the mirror glass carefully a minute or two after activating the feature to check for warmth.
- Compare both mirrors if only one seems affected, to help confirm it's the mirror rather than the whole system.
- Have a shop test the heating element and wiring directly if fuses check out fine.
- Replace the mirror glass or full assembly if the heating element itself has failed, since it typically isn't repairable.
Tools and parts
- Fuse puller/tester
Heated mirror glassSearch: “heated side mirror glass for [year make model]”
When to call a pro
A shop can test the heating element directly with a multimeter to confirm the exact cause before you buy a replacement part.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.