What do you do when a customer with a Toyota Prius hybrid says his Check Engine light is on and wants you to diagnose his problem? Can you do it? Or, would you send your customer back to the Toyota dealer?

To help alleviate anxiety over the complexity and reliability of its hybrid systems, Toyota gives the buyers of its hybrid vehicles an 8-year, 80,000-mile warranty on the hybrid components (10 years, or 150,000 miles for hybrid owners in California).

Consequently, if a Prius is still under warranty, a motorist can return to his Toyota dealer for free diagnosis and repairs.

The Prius first appeared in model year 2001. Although eight years has not yet passed, some of these early models have probably accumulated enough mileage to be out of warranty - which means they are fair game for the aftermarket as far as the hybrid components are concerned. And any system (brakes, cooling system, tires, suspension, etc.) that is not under the hybrid warranty or original factory warranty is also fair game for aftermarket service and repairs. So don't pass up these vehicles because they are hybrids.

Prius Relay Engine Box (click on "zoom" tool for full view)

If a problem occurs with something that's not part of the hybrid system, diagnostics is essentially the same as on any other vehicle. You troubleshoot the fault, do your diagnostic tests to rule out various possibilities, and hopefully zero in on the faulty component tha...