Gen II car shaking / p0301

Hey guys,

Really like the forum, read a lot and this is my first thread.

I bought a second hand 2005 prius (gen II) at 125k km.
I am looking for some tips on what might be the problem with my prius.

Soon after I got the car I got p0402 and p0505. After clearing the errors, I got back only p0420.

About a month later, my car started randomly shaking both when accelerating and at idle.
This happened 2 or 3 times in the span of 2 weeks. The CEL and traction control light started flashing. I stopped the car and started again like absolutely nothing happened 10 seconds ago. (This time I got only p0301.)

Yesterday, the situation with the shaking was horrible and I got p0301. Naturally, average fuel usage went up a lot. Even at idle on the parking lot, I turn on the aircon so the engine would start - the feeling is like the car is going to collapse any second.

I have recently used a new gas station, so I thought possibly bad fuel. However, if it was bad fuel, i should have gotten all misfire mistakes, right (p0300~p0304)? Please correct me if I am wrong.

So if I am getting only p0301, the problem should be either the spark plug, injection coil, fuel injector etc. for cylinder 1.

My car is currently at the mechanic's place, so all of the above are being checked as we speak.

However, what I am worried about is that this shaking / lights flashing drama is happening at random. If it was any of the above, shouldn't is just happen all the time? When I went to the mechanic yesterday, I barely made it there. He was busy, I waited for 20 minutes, then he wanted me to drive the car for a bit to see the problem. This time the car was working like a brand new car. Absolutely nothing happened. He probably thought I was crazy.

So yeah, he will closely inspect spark plugs, injection coils, fuel injectors etc. If all of them are fine, where should we look next? Any suggestions are more than welcome.

Head gasket leak perhaps?

 

Thanks for the reply JC91006!
I don't know about cars (this is my first one), but if it was a bad coil, shouldn't the symptoms of my problem happen all the time and not sometimes at random?

And sorry if this sounds stupid, but what is SM-N900P?

 

Hey guys,

Thanks for all the feedback. This is just a quick follow up.

Got my car back. So far so good.
Turned out is was the spark plug for cyl 1. The other ones were not great as well.

Replaced 4 spark plugs, replaced MAF filter, changed oil as well.
The mechanic said the coils looked fine and I didn't have to change them right away.

The car is running very smooth right now. No codes no nothing. Hope it stays that way.

Again, thanks for the quick feedback - this forum is great! Managed to learn a lot about my Prius!
If anything else happens regarding this problem, I will update the thread.

 

Thanks for the feedback.
Prior to changing the plugs and the filters today, I have experienced those occasional "slight hesitations" during acceleration as well.
After taking it from the mechanic today, I did a 60km drive for fun, all seemed fine, no hesitations apart from the general millisecond hesitations from the HV battery/engine switch.

Again, thanks for the all the comments and feedback!