However, it did that intermittently for a few days with the lights coming on and rough running. But it went away after a few days of that.
This year, the problem has come back--same time of year--and it's much more frequent and worse (at one point, the car was practically shuddering from the rough engine). So I decided to buy an OBD reader and check the codes. The OBD shows code "P0351". In looking at that code on RepairPal (https://repairpal.com/obd-ii-code-p0351), it says this:
Code: Select all
Common Problems That Trigger the P0351 Code
Defective Ignition Coil(s)
Defective Spark Plug(s)
Intake Manifold Vacuum leaks
Carbon buildup in the Throttle Body air passages
Defective Idle Air Control Valve or Electronic Body
Now, from what I've read, the first two are the most likely culprits. But my question is--if either the ignition coils or spark plugs were defective, wouldn't they cause the rough engine symptom constantly, rather than intermittently? During the intermittent times those three dashboard warning lights are off, everything seems fine, so I'm wondering if I should bother replacing the ignition coils and spark plugs, or focus on trying to run through the other three...?