# Magnet Test Reveals Used Car Repairs

> A magnet test spots body filler on used cars but has limits.
- Title: Magnet Test Reveals Used Car Repairs · Family Handyman
- Summary: A magnet test spots body filler on used cars but has limits. Bringing a magnet to a used car can reveal past repairs but doesn't guarantee safety.
- Keywords: magnet test, used car, body filler, car repair, trinity audio, ftc, Magnet, Test, Reveals, Used, Car, Repairs
- Source: Family Handyman — https://familyhandyman.com/article/magnet-buying-used-car
- Author: Alex Shoemaker
- Published: 2026-10-02T16:49:02+00:00
- Read time: 1 min
- Topics: magnet test, used car, body filler, car repair, trinity audio, 3m, ftc
## Magnet Test for Used Cars
Bringing a magnet when buying a used car can reveal signs of body filler and past repairs.
## How the Magnet Test Works
Place a magnet on steel sections to check for weak pull indicating body filler or past repairs.
## Magnet Test Limitations
Magnet won’t stick to aluminum, fiberglass, or plastic parts, and may miss some repairs.
## 3M Bondo Body Filler
Bondo® Body Filler shapes in minutes and fills holes and dents for steel panels.

> Bondo® Body Filler shapes in minutes and will accept as many reasonably applied applications as required to fill holes and deep scratches or dents
## FTC Recommendations
The U.S. Federal Trade Commission advises getting a mechanic’s inspection before buying a used car.

> That’s why it’s always a good idea to pay for an independent mechanic to conduct a mechanical inspection of a used car
## Why the Test Fails
A magnet test can’t show repair quality or mechanical condition, only potential areas needing attention.
## Key takeaway

Bringing a magnet to a used car can reveal past repairs but doesn't guarantee safety.