Ignition Coils, P0171, P0174

[pgill]

I agree with oragex

The thermostat is known to fail at about 10 years

And there is some evidence that a failed thermostat can cause ignition coils to fail

If you do replace the thermostat let us know if it failed

The failure will be obvious the spring will be in the engine block instead of in the thermostat housing

Good luck

Paul