P0003, P0103, P0203, P0403, P0300, P0301, P0302, P0304

Good morning.

Last Sunday night, my 2005 Prius (about 240,000 KMs) developed a minor shudder in the engine. I had been driving it about five minutes when it started. Ambient temperature was about -5 C. As I drove along, the shudder got worse until it became quite violent (especially when the engine was at or near idle speed). When idling, and battery charging kicked in, the shuddering was even worse. No check engine light came on that night. There was a distinct loss of power when accelerating.

Then last night, I started it and it sounded normal (it was a relatively cold night, about -12 C). It drove well until about five or so minutes had passed, at which point the shudder started and became rather violent right away. Then a check engine light appeared. I plugged in a little wifi reader I have, and downloaded the DTCs to my phone:

P0003, P0103, P0203, P0403, P0300, P0301, P0302, P0304:
Multiple cylinder misfires
Fuel volume regulator control circuit low
Mass or volume air flow meter circuit high input
Injector circuit malfunctions
Exhaust gas recirculation circuit malfunction

When the engine shuddering started, the coolant temperature was around 40 C. When the engine is cold (like below zero cold), I don't detect any shuddering or loss of power.

I'm in the dark here. Any thoughts? I had always assumed the HV battery would be the first thing to go (the car is 14 years old, after all).


Thanks for reading,

Sylvan

 

Thank you SFO and Patrick for your thoughtful replies.

I'm including the prices (in CAD $) of items I bought today as a reference for any other local Prius Gen 2 owners in the area who may see this.

The code reader I'm using is some generic thing from Amazon (Etekcity Super Mini Wifi, $28.30, no longer available, purchased in 2015 for fun, years before my car ever threw a code). I don't remember why I chose it. I use it with an app on my iPhone 5 called Car Scanner Pro ELM OBD2 ($6.31 from the Apple App Store).

Here in Montreal, I am using 5W-30, as specified in the manual and on the oil fill cap. I have tended to use synthetic over the years. Is there a weight of oil you recommend I use instead?

This morning I got up early and cleaned the MAF sensor with CRC SensorKleen Mass Air Flow Sensor Cleaner ($10.91 from Canadian Tire). I let it dry thoroughly before reassembling it. I did not touch any of the sensors. I also cleaned, to the best of my ability, the throttle body intake and plate with CRC Throttle Body Kleen Intake Cleaner ($12.06 from Canadian Tire) using a clean rag and a toothbrush. I did not drown the throttle body in cleaner fluid. Below, the MAF before cleaning:


At noon I replaced the spark plugs with four new NGK IFR5T11 ($64.35 from Canadian Tire). I used a torque wrench and followed the instructions in this post (minus the anti-seize on the threads): How to Replace Gen II Prius Spark Plugs and PCV Valve | PriusChat .

Here is what the spark plugs looked like (I have no idea when they were last changed, if ever):


A couple of things:
There was some dirty water in the first (the leftmost when viewing the engine from the front of the car) spark plug hole / valley / whatever it's called. I soaked up what I could with a rag. The upper, metal part of that first spark plug was rusty. In the past, I have seen water pooled around the rubber seal of that first ignition coil after rain and often during winter. I hate how water collects there. I wonder if this has maybe caused a fault in the ignition coil which is causing the misfiring / knocking.

The fourth injector connector (rightmost) was full of oil. The others were not. Why might this be?


I removed and inspected the PCV valve. I could not find a replacement PCV valve locally today, so I put it back. I did not know what I was looking for while inspecting it, but it rattled when I shook it and didn't look very dirty at all.


Thanks again for your help.

Sylvan

 

Hello again. It's been a few weeks. Patrick, thank you for your comments.

A little update:

For two weeks after changing the spark plugs, the engine ran fine. No detectable misfiring, no check engine light; ran like a dream, really!

But then it started again. As usual, only when the engine warmed up. It's spring, so it's been raining a fair bit, and maybe that was part of it. After a week or so, it got so bad that the car began to feel under-powered. So today I went to an auto parts store and bought a single new ignition coil (a YEC Flamma for $104.17 CAD). It was the cheapest one I could find (they seem to be more like $25 USD on amazon US, but I'm in Canada, etc. etc.). I suspected the first cylinder was the one misfiring, so I changed out that coil with the new one and the problem immediately went away. Now, it's only been a day since I replaced it, but it seems positive.

The #1 coil I removed looked to be in pretty good condition, although it had a ring of rust around the lower portion.

I also bought some black RTV sealant and sealed the gap between the two plastic cowl pieces. Not a pretty job, but I believe it will help prevent the top of the engine from becoming a swimming pool again. Interesting that there was a TSB about this in 2004.

I have gotten no further in diagnosing the oily substance in the #4 injector connector. I don't believe anyone spilled oil there (it seems unlikely, given its distance from the oil cap). I can't tell if there's oil leaking from the valve cover, but I haven't really gotten in there and had a good look yet. Would fuel turn into what looks like oil? I figured it would just evaporate; but then, I am no expert.


Thanks again.

Sylvan

 

Hi PapaWill,

As I wrote in late March, replacing the #1 ignition coil solved the misfiring problem. Eight months later, the car is driving well. I don't know if your car is experiencing the same problem as mine, but changing the coil instantly fixed it for me. If you buy a single new coil, you can just switch it out with each of the four coils in the engine, one by one, and see if the misfiring goes away.

As for the oil I found on top of the engine, I stopped worrying about it. The engine burns a tiny bit of oil, so I periodically top it up. Seems fine.

Good luck to you.


Sylvan