Life expectancy for Ignition Coils ?

Mine are fine at 200k miles (2004 Prius). As long as they don't get wet, they should last indefinitely and are not a preventive maintenance item.

JeffD

 

If you did have a failure, it would illuminate the check engine light, but the car is still drivable. The main problem is that it can be difficult to differentiate a failed coil from a failed fuel injector.

 

I find that it is easy to differentiate the two problems if you can read the codes. Just swap two of the coils and see if the problem moves.

JeffD

 

Ignition coils are simple devices electrically consisting of two coils of copper wire wound on an iron core. Faults come in three forms,
(1)Shorted turns between coils (not common).
(2)Open circuit coils, normally due to poor termination of coil ends (not common).
(3)Insulation breakdown due mainly to moisture, but can be caused by a loose or badly seated spark plug giving carbon blow bye and burning of insulator making insulation break down the most common and sometimes preventable reason for failure.
Large spark gaps or fouled plugs will not cause coil overheating but may break down the insulation due to higher unloaded coil voltages, but in the ideal world the coils should be designed with this in mind. I hope this helps with understanding ignition coils.

 

The Prius igniter (aka ignition coil) is more complex than a simple transformer. It includes a power transistor which switches the flow of 12V current to the transformer. Hence, the engine ECU only has to switch each of the four transistors (one for each igniter) on and off in the correct firing order sequence.

Nevertheless, in response to the OP's question, there is no reason to replace the igniter unless you have a misfire DTC and have determined that the igniter is at fault, or if you see burn marks or rust deposits on the plastic body of the igniter.