Rick's Free Auto Repair Advice

Pre-purchase inspection before buying a used car

Pre-purchase inspection — Why you need one before buying a used car

Until you’ve inspected the underside and run a full scan tool read, you haven’t inspected a used car

I’d don’t care how long you’ve been kicking tires on used cars, on modern vehicles, you can’t possibly know the condition until you’ve connected and read a scan tool or had it up in the air to check the underside.

What do they check on a pre-purchase inspection?

They check the underside

Once the shop has it up on the lift, they check for all these things:

CV boot condition
Steering linkage condition
Ball joint and control arm condition
Strut, shock and spring condition
Engine oil leaks
Signs of rust through on critical frame components.
Signs of cooling system leaks.
Brake and rotor condition
Tire tread depth, wear and condition

A pre-purchase inspection includes a scan tool check for trouble codes, bad live data and readiness monitors

Unscrupulous sellers often clear trouble codes to make it look like the vehicle is in good condition. That also resets all the readiness monitors. If you don’t check those, you could find yourself with trouble codes within a week of buying the vehicle.

A scan can spot recent code clearing and live data that signifies an upcoming problem.

They check the engine compartment for signs of needed replacement parts

Air filter
Ignition parts
Cooling system condition and oil leaks
Engine oil dipstick and condition
Transmission fluid level and condition
Coolant level and condition
Brake fluid level and condition

A pre-purchase inspection should include a test drive

The tech will check for

Good start and idle
Good acceleration
Good braking
Steering — responsive with no play
Ability to stay in its own lane
Comfort and stopping ability of struts and shocks
Shift quality, downshift, delays, flares
AC and heat operation.
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Posted on by Rick Muscoplat

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